From your screenshot it looks to me like when you are loading the symbol catalog, you are going into the artwork folder itself, picking an image and hitting OK instead of loading the .FSC file in the parent directory.

The reason this is important is that all such settings are store in the symbol catalog file (the .fsc). Going into the artwork folder and picking an image is an alternate way of getting the images into the symbol catalog window that is best suited for when you have a folder full of artwork that has NOT been made for CC3+, i.e. it doesn't come with a symbol catalog file. But loading it this way just loads them as "dumb" images, nothing of the smartness of the CC3+ symbols will come with.

So for any official or properly prepared CC3+ symbols, always load it through the symbol catalog file, not the artwork folder.

Yes and no.

The default grid command in CC3+ can't create such grids, but you have some options.

1. Make grid, then simply rotate it (You may need to unfreeze the layer it is on first)
2. Use symbols, these are rotatable.
3. Use a symbol fill based on some simple line symbols. You can specify rotation for this type of fill.
4. Use a fill that contains a rotated grid. If using a raster image, you can rotate it either in an image editor outside of CC3+, or you can use a shaded polygon inside CC3+ to apply rotation to the fill.

All of them require some manual work, as drawing at an angle like this isn't something CC3+ has tools to do directly.

Note that since CC3+ can't have a rotated snap grid, you may wish to simply draw it "normally" first, and then simply rotate the entire dungeon with the rotate command.

If you only want smaller symbols, that is quite easy. After starting a new map, just hit :CC2PRESETS: and change the default symbol scale to whatever you want. If you want 5 times smaller, just set it to 0.2.

Note that this just changes the default scale, not the current one, so either save, close and reopen the map as this will open it with the new defaults, or simply click a symbol, and with the symbol on your cursor click in side the map area to bring up the symbol parameters dialog and hit "set normal" and the current setting should be changed to the default.

All tools that place symbols should observe that default setting.

This is a special case that happens with symbols. The thing that happens is that all symbols have their definition on the SYMBOL DEFINITION layer. And if you hide the definition, the symbol disappears. So symbols will always be hidden either if you hide the layer it is on, OR if you hide the SYMBOL DEFINITION layer. So if you are trying to get to an entity by hiding all the other layers, make sure you leave SYMBOL DEFINITION still visible.

As JimP says though, it shouldn't be on the MERGE layer, so use change properties on it to put it somewhere else.

They only affect the current CC3+ session. The default at launch should be smart symbols on, but they won't reset by simply loading a new map.

Note that you can also find the same setting in the symbol parameters dialog (the one you get when right clicking with a symbol on the cursor)

Disabling smart symbols disables everything that is smart about symbols, like connecting symbols, control points, random selections from the catalog, etc. Basically, they lose all behavior and gives the user full control.