I was just thinking about it, and are thicker or heavier strings better for low tunings like dropped Db and C than a light or medium string? Does it not make a difference?
Yes, they're better for lower tuning, but, you'll notice a lot more tension when they're tuned in standard.
Yes, heavier strings won't flap around as much as regular strings when you go to a lower tuning.
i put a thicker low e string on for dropped d tuning. the one that came with the set was very rubbery feeling.
I was trying to play Queens of the Stone Age (they often play in C Standard) and he uses Super-slinky strings, and it was almost impossible because the strings were so flimsy
sometimes they are better.

It all depends on your guitar. The scale length, bridge type, how it's set up.

I have a guitar set up for CGCFAD, with 9-42 strings. Due to the way its set up, thats the best string gauge for that tuning.