That's way to high. You shouldn't go higher than 40000000. You can easily calculate that number yourself. Take that 6000x6000 that you manage to export, multiply that up, and you have 36000000. That's your practical limit for how much large a map export you can do in a single pass. If you set the ppp value higher than you can handle, you'll end up making your max possible single pass size your absolute max as well, because CC3+ won't be allowed to go for more than one pass.

The vegetation for DD3 is found on the Skirmish button (the last one).

The lines have a fixed length. They are then scaled based on the width of the drawing, so if that doesn't match the ratio, they don't end up being long enough, or alternatively, too long. The new map wizard doesn't distort images, it always scales them proportionally. ()

In that case, I think it is best that you put in a tech support request. You'll find the form on your registered user pages. They should be able to get you back up and running.

Since CC3+ always tries to open the last map on load, there is a chance that something has gone wrong with it.

First, to open CC3+, try to either double-click on another .fcw file on your drive, since that will open CC3+ with that file instead of your map, or rename your map file before starting CC3+, since this will cause CC3+ to not find it and will open up without a map (showing a black screen).

After that, you can try opening your map using File -> Open. If that crashes CC3+ immediately we know where the problem lies and can take it from there.