Joannesalfa - That doesn't really adress the concern about slopes though
— - Regarding question #2. I obviously can't speak for Ashley, but I'd hazard a guess that as far as C2's innards and runtime efficiency is concerned, a Tilemap would have the same effect as if you used several small sprite objects instead of one big one. The Tiled Background object works on the same principle, just that Tilemap allows for more than one tile.
I have some thoughts about the Tilemap as well.
First off, love it. C2 has needed this kind of feature for a while now and I'm happy to see it. That said, improvement is always an option.
1. While trying out the Tilemap object I found myself accidentally moving the object around at times. Locking the layer makes you unable to edit the tilemap. I think a way to lock the Tilemap object in place, but still be able to edit it, would be a good idea. Maybe even necessary.
2. I second the idea of more "advanced" editing tools. Copy/Paste, select and drag, and being able to make stamps of a certain set of tiles would be nice features to see in the future. Of course, Tiled has some advanced features we could use in the meantime (or instead?) but it would be nice to see it in C2 down the road.
3. Speaking of Tiled. It has a feature that lets you add properties to the tiles. This could be usefull for a wide range of different things. Having tiles be of different materials for instance, changing the sound effects when walking on them and such.
4. Loading and editing tilemaps at runtime. I'm guessing the use for this is pretty self-evident. Ingame level editors, animated tiles, etc.