My suggestions

Status
Fixed
Issue description

Baby mobs
make mob spawn only in overworld
Change knockback mob does

And also to be able to make a block not connect to fences or suffocate you.

Issue comments

You can make mobs only spawn in overworld by limiting biomes it spawns on. For knockback, if you mean ranged mods, this is planned.

To make blocks no suffocate you, you can select to make a block not collidable.

I don't think there is a way to make a block not suffocate you but being collidable at the same time.

Try giving it transparency, I heard (but I'm not too sure) that transparent blocks don't cause suffocation