Chip's Challenge Creator

[The Architect]

a copy/cut/paste level feature would be nice, the kind which the old old, CCEdit had (or something similar)

All the CC1 editors have this feature, and CC Creator will be no exception.

also what's your stance on invalid tile combinations? For example placing a no symbol without items allowing new (unintended) behavior. Will this kind of thing be possible in this editor?

My general plan is that with some advanced editing, you can produce any kind of invalid combination you please.

However, elements like the forbidden sign and directionless frame blocks will be freely placeable by default. I see no reason to limit the kinds of puzzles you can make using them.

In contrast, elements like clone machines with multiple directions, while possible, are completely useless, so you'll need to do advanced editing to place such elements (if you really want them).