If it does this, it is a) not very well advertised and b) pretty stupid. I haven't noticed anything to suggest it hits for less after the initial hit and if anyone had actually used Ball Lightning they would know, just like Nether Tentacle, it has the potential to hit the same target multiple times. I may try out Nether Tentacle again but my experience so far with Act 2 is if I get hit I die so what use is life steal?
And no I don't bother with hatred generating attacks. Bat Companion + Templar + equipment has given me 8.6 ish (and my gear is extremely poor and in dire need of an upgrade). I am finding many occasions where I start to run low on Hatred lately but I think this is more due to my terrible equipment meaning that Ball Lightning/Impale/Caltrops aren't doing enough damage so I use more than necessary.
I've seen it stated quite a few times about the ball lightning damage but I haven't done the math myself. I've read things about the 155% damage being only if it hits a target twice and that it's just another bugged/error tooltip. So essentially it hits at around 75% compared with NT which hits at 155% with each hit. And with NT, if it crits, it'll crit everything it hits which afaik Ball Lightning doesn't do. That's why it's a staple in many builds, if you find the reduced damage/possible stun to be more useful then okay, but typically NT does more damage and thus when you're trying to down mobs as quick as possible, it seems like the better damage choice.
Oh right. That's something I haven't seen before. Have you had to sacrifice other stats in order to get the hatred regen or have you managed to bag some good deals/items?