Thanks in advance for any answers i can get to these.

1) Is poison shot worth useing? It appears to re-apply itself before it is able to deal any damage. Does it stack with itself or am i just wasting mana placing it on my left mouse button.

2) Weapon speed, what is best? I have a Freakin fast crossbow and a grandma shot gun. Both seem to give roughly the same dps. So which would be better?

Thats it for now. Thanks again for any info.

I have a passive on my right mouse button, so that I can auto attack with it. I have poison shot on my left mouse button, and use it once to start off each new mob I'm killing.

Speed.. well, its up to your personal taste. Just like the fighters have fast one handers and slow two handers, we have fast xbows and slow shotguns.
Generally, slower = higher min/max damage. If you hardly ever miss, then slow can be quite good. Shotguns do tend to have a shorter range then xbows. Fast = lower min/max damage, but you also shoot so much faster that comparing just the range to a shottie isn't fair. Do some dps calculations.

I would recomend a normal speed X-Bow.... just my opinion.
I have Putrid on my left and Poison on my right (when Im playing Poison Ranger)
Sometimes I use smackdown on my left and Poison on my right... seems to really work for me.