We'll leave all of that up to you! Go with whatever you think will be the most fun to play with -- if you want him to still be able to eat/kiss people/etc while still being stuck in the costume, it's totally fine for him to be able to lift it up just enough for that while still technically being "stuck" in it and unable to take it off.

As for the lacy lingerie... it can be as scanty and scandalous as you'd like it to be, or just regular lacy shorts. Whatever you'd like!