If a servent have like 4 hits in the buster, the damage would be the same as if he was with only 1 hit?
Usually each hit ends up doing less damage than one big hit but depending on attack value and madness enhancements, they usually add up to the same amount in total as one hit from a different servant would do, all those things being equal. Multiple hit Buster's are just advantageous as they can get more np in arts buster buster or any chain starting with an arts card than a single hit does. Same thing with quick card starting the chain and star generation.
No, as far as I know. The hits only change NP gain for hit and animation. From what I hear from my friend Bryn and Scat deal the same damage when they're the same level with the same attack fous and attack stats...though I couldn't confirm since you need both servants with the same attack stats, but different hits to test.
Number of hits affect only star and NP gain... Almost. There are few "On-hit" effects (look bound CEs), they work on each hit. Like David have 10% chance to kill target on each hit. Add 2xShiki, and for one turn, he'll have something like 3% chance on each hit to kill servant. Grandpa Hassan can cry in a corner.
