Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

Does regneration items and spells stack whit eachother?

yes

You cannot cast the same spell twice on yourself, like Regenerate and Regenerate on yourself to gain +20 HP a round, instead of the usual 10.

But otherwise, yes

Also, the spells of the same "line" do not stack with each other. For example the Vigor spells do not stack with each other.

ring or regen and cloak of regen will provide +1 , +1 hp a round, and sometimes you will even see it say +2 that round...

Yes..

You can take Horned Devil/troll shape, have a bard sing about you being a devil/troll and regenerating with the inspire regeration and have Regenerate cast on you for massive regenerative ability.

Or wear a cape (and if you have, a ring but they're super rare) and the same for a lesser effect.

What about those Epic feats Fast healing? Will those stack with vigors, regenerations, regen items?

I just saw the topic and became curious after seeing those feats were added

Yes.

bard regeneration really needs to be improved while we're on the subject. It ticks like once every 3 rounds, heals for less then regeneration, and is simply worthless given you have to give up hit/damage or AC song to activate it.

If changed to tick once a round I can see some use of it.

It's every 2 rounds actually. I find it pretty cool as it is to be honest, just don't use it while fighting but in between.

Just have bunch of bards team up, each using a different inspiration, and you will 'rock the world.'

get like 5-6 bards and go NUTS!!!