No, not reinstall CC3+ itself, but the latest update (Currently update 27). The update fixes things not just with the core CC3+ install, but also updates files from the add-ons which is why it should always be installed after installing an update (or at the end if you install several in a row) even if you have installed it previously.

1. When you hit the add-on buttons the program loads some defaults to ensure that things work sensibly. For example, if the overland filters were kept when you went to the DD3 add-on, all catalog buttons would just return empty results because the overland filters doesn't make sense in a dungeon setting. Unfortunately, this also means that the settings loaded with the map is lost. Generally, it is not adviceable to use these buttons in the middle of a map. If you wish to load symbols from a different add-on, use :ICON_CATALOG: instead, this allows you to load any catalog, not just the one provided by the defaults for whatever add-on you switch to. The easiest way to reload the correct settings is to just reload the current map, you don't need to restart the program. Simply save the map (if you have changes you wish to keep), then simply pick the map from the top of the recent file list in the File menu. This will reload the map, and reload the settings from it.
2. One way of making torn edges is to place a white polygon with some fractalized edges on top of everything. The white will cover up part of the map, appearing as a tear. Add some inside glow and perhaps some blur or similar to make it look more like a tear and not just a flat poly.

You can change the default wall to be whatever you want. The :DD2WALL: button just starts the drawing tool named Wall, Default. You can edit this to change the properties (advisable to make a copy of it first to preserve the original, but if you want to edit the tool that is used by the button, you of course have to edit the original, and just keep a copy under a different name as a backup). To make it cutable, all that is required is that it is on the WALLS layer. From your images, you are using SS4, and I don't seem to have a problem with doors cutting that wall though.

To make them into single walls, you need to do some manual work. Erase the entire wall (one of them) where there is a complete overlap, and use tools like :CC2BREAK: to split and cut parts out of walls where you have a partial overlap and don't want to delete the whole length of the wall.

In addition to what Sue is writing above, check for double walls. When I look at the screenshots you post, the door is clearly cutting something, otherwise there wouldn't be a white rectangle there. And the wall fill pattern in the second image is offset from the first one, indicating that there seem to be two walls on top of each other there. (The wall cutting functionality only cuts one entity)

Latest three royals added to the atlas:

It's usefull when you want a set of shades from a different base color than the ones from the default palette.

I find it a nice resource. It should install fine with CC3+, but the procedures do require some manual unzipping of some zip files, so it is important to unzip these exactly as described in the guides, as ending up with one more or one less folder in the path is guaranteed to lead to red X'es.....

The difference is because the command increases the number of pixels that will be handled in each pass. This means that a bigger chunk of your map is processed in each pass, and therefore requiring fewer passes overall.

If anyone want that final macro from my stream, here it is:

LWIDTH 0
FSTYLE Solid
COLOR 0
POINT ^DPick starting point;
SPOLY
@0,0
@-0.55094,0.05149
@-0.41707,0.08238
@-0.2523,0.06694
@-0.4943,0.19051
@-0.31408,0.16477
@-0.37588,0.26774
@-0.19566,0.18537
@-0.14932,0.16991
@-0.21111,0.32953
@-0.12872,0.31409
@-0.06178,0.2523
@-0.02575,0.21111
@0,0.31923
@0.02575,0.22656
@0.06178,0.27804
@0.10813,0.32439
@0.19051,0.41191
@0.06179,0.09783
@0.06179,0.53034
@-0.0103,0.35013
@-0.09268,0.47886
@-0.08754,0.77749
@-0.06178,1.06068
@0,0.53549
@0.0103,0.00515
@0.01029,0.40677
@0.04119,0.38102
@0.06694,0.37073
@0.10298,0.31924
@0.12872,0.27804
@0.33984,0.67451
@0.19051,0.33983
@0.40161,0.63333
@0.40162,0.50459
@0.38618,0.36558
@0.35013,0.2317
@0.242,0.10813
@0.30378,0.07208
@0.27805,0.08754
@0.31409,0.14417
@0.19051,0.10813
@0.29349,0.20595
@0.2317,0.19567
@0.33983,0.36042
@0.2523,0.33983
@0.09268,0.16477
@-0.02059,0.14417
@-0.00515,0.2626
@0.01029,0.15961
@0.06179,0.33469
@0.14932,0.45826
@0.2317,0.44795
@0.21111,0.29349
@0.21626,0.21626
@0.24715,0.16991
@0.39647,0.19567
@0.12872,0.10812
@0.07724,0.10298
@0.11842,0.2729
@0.12873,0.24715
@0.26774,0.40161
@0.17507,0.18022
@0.07723,0.05664
@0.09783,0.04634
@0.13902,0
@0.07209,-0.05149
@0.05149,-0.07723
@0.06693,-0.21626
@0.04119,-0.29864
@0.02575,-0.80839
@0.00515,-0.09268
@0.0206,-0.03604
@0.06178,-0.04119
@0.11843,-0.04119
@0.43766,-0.11328
@0.19566,-0.08753
@0.10298,-0.06694
@0.08753,-0.08239
@0.15962,-0.24714
@0.16992,-0.19052
@0.2111,-0.14417
@0.32439,-0.11842
@0.08753,-0.08753
@0.03089,-0.09269
@0,-0.23685
@-0.03089,-0.14417
@-0.08239,-0.20596
@-0.16476,-0.25745
@-0.10813,-0.11327
@-0.15447,-0.12358
@-0.38617,-0.23685
@-0.21111,-0.15447
@-0.06693,-0.08238
@-0.0412,-0.08238
@-0.01029,-0.05664
@0.01029,-0.21111
@0.13903,-0.84958
@0.06693,-0.63847
@0.01545,-0.4943
@-0.0206,-0.37072
@-0.04119,-0.29349
@-0.10813,-0.41707
@-0.16476,-0.36043
@-0.17507,-0.25229
@-0.15447,-0.18537
@-0.2317,-0.33983
@-0.23685,-0.44281
@-0.12358,-0.31923
@-0.08753,-0.40162
@-0.0103,-0.90107
@-0.01029,-0.00515
@0,-1.7455
@0.01029,-0.00514
@0.0103,-0.65392
@0.0206,-0.18536
@0.04119,-0.08239
@0.10298,-0.06693
@0.14932,-0.04119
@0.35013,-0.0515
@0.16476,-0.06178
@0.05664,-0.05149
@0.02575,-0.05664
@-0.0103,-0.18536
@-0.06179,-0.12358
@-0.07209,-0.07208
@-0.10297,-0.05664
@-0.05664,-0.0103
@0.06179,-0.14417
@0,-0.15962
@-0.04634,-0.09268
@-0.09784,-0.08238
@-0.20081,-0.08239
@-0.27804,-0.06178
@-0.30893,0
@-0.24201,0.06178
@-0.15961,0.08239
@-0.22141,0.16991
@-0.17506,0.19566
@-0.08753,0.12358
@-0.14418,0.23685
@-0.14932,0.29349
@-0.29864,0.68481
@-0.02574,-0.20081
@-0.12873,-0.31408
@-0.16991,-0.242
@-0.14417,-0.13903
@-0.10298,-0.06693
@0.41192,-0.02575
@0.33983,-0.06179
@0.21111,-0.08238
@0.10812,-0.07723
@0.06694,-0.07209
@0.04119,-0.07208
@0.02575,-0.09783
@0,-0.13903
@-0.02575,-0.11842
@-0.05664,-0.13902
@-0.11842,-0.06694
@-0.2626,-0.06179
@-0.36558,-0.04119
@-0.35527,-0.0206
@-0.90622,-0.00514
@-1.35933,0.04634
@-1.05038,0
@-0.72601,0.04119
@-0.42736,0.06179
@-0.09268,-0.31924
@-0.0103,-0.31923
@0.05149,-0.24715
@0.07724,-0.16477
@0.15447,-0.21111
@0.08753,-0.08753
@0.18536,-0.14417
@0.25745,-0.14932
@0.38102,-0.15447
@0.2523,-0.07723
@0.40162,-0.08754
@0.43766,-0.06178
@0.33983,-0.02575
@0.88562,0.00515
@0.52519,0.06179
@0.11328,0.03089
@0.42222,0.06694
@0.4634,0.04119
@0.26775,0
@0.18021,-0.0206
@0.13902,-0.04119
@0.04119,-0.02574
@0.0309,-0.04634
@0,-0.03605
@-0.02575,-0.05149
@-0.07723,-0.07208
@-0.28834,-0.16477
@-0.37588,-0.14932
@-0.76719,-0.2317
@-0.40162,-0.08753
@-0.54579,-0.08239
@-0.42221,-0.03089

And yes, it is actually two blank lines at the end of that one. You may wonder why, since I spesifically said "only one line" in the video, but this is an exception, because the SPOLY command is actually split over multiple lines here, and the first blank line isn't repeating this command in this case, it is empty to signal no more coordinates, done drawing. But if I had added an extra, third line, here, then it would have tried to repeat SPOLY again, requesting coordinates from the user.

The Digital overland comes from the Vintyri Cartographic Collection.