First of all, the DC levels are played with the R'n'D game engine, although the original DC engine is closer to the EM engine (especially with regard to the fact that the player can move every single frame in the R'n'D engine, while the player can only move every eight frames in the EM and DC engine, which makes quite a difference).
So this "asynchronous handling of game elements" (as in the R'n'D and also the original Supaplex engine) is the most apparent difference to the BD and EM (and DC) game engines, which handle game elements synchronously every eight frames.
As the original DC engine is closed source, exact behavior can only be guessed by playing the game, not studying the code, unfortunately.
pretty sure the bombs use to drop then explode. They would only explode the tile you were just on and the 5 adjacent ones.
Yes, if a bomb falls down, it explodes -- the field where the bomb was, plus all eight surrounding (adjacent) tiles. If one of these adjacent tiles is also a bomb, it also explodes (potentially resulting in a chain reaction if there are a lot of bombs).
This works the same in R'n'D, EM and DC.
There's certainly some weird behaviors that are not native to DC 2 and 3 (idk if 1 is different or even which game engine these levels are currently played on)
The original DC2 and DC3 game engines should work the same as the DC1 game engine regarding bombs.
Could you describe what you experience as "weird behavior" when playing DC levels in R'n'D? Some differences could be adjusted to work more similar as in DC.
I think when rocks are cracking nuts they also fall off too quickly.
I will compare this in both engines, but this should not make a big difference regarding playing and solving levels. Or does it?
and when pushing rocks they always push at the same interval where as I remember have them had a random amount of pushing time before they would move.
Rocks are pushed at random intervals in both the R'n'D and EM/DC engine, but it works differently. In R'n'D, there is a delay between 8 and 16 game frames before a rock that is being pushed really moves. In EM/DC, there is a random chance that a rock that is being pushed really moves, which is checked every eight game frames. This may result in rocks being pushed faster than in R'n'D, but may also result in a much longer pushing delay. Maybe I could adjust this for DC levels in R'n'D.