Several questions but we will start with one
 

So I was at a friends house when he looks under the front passengers side of my truck to see how bad my shocks are (freakin bad) and he proceeds to tell me that my shock mount has seperated from the frame. And when it did it hung down and completely ruined my cv joint. so the question is. Is this fix worth it. Is welding it safe. And will a leveling kit or lift kit cause it to happen again?

This is just my oppinion and I'm sure you will get other DIFFERENT opinions. But I wouldn't weld it. I would remove the broken rivets and drill out those holes over sized for some #8 grade bolts. in place of the rivets