(Can my team say, sign someone to a 4 year contract then turn around and buy it out the following year)?
Can buy it out the following morning if they like. Understand what a buyout is, though. A buyout isn't just a waiving - a buyout is a colloquial term for a waiving that is accompanied by an agreement to lower the amount of outstanding money. You can cut anybody you like at any time, but a buyout is a mutual agreement, and it takes two to twerk.
And when does it come off the salary cap/how does it affect it?
Whatever the amount you agree to pay after the buyout is the amount charged to the cap. So if a player is owed $10 million, and they agree to buy him out for 80% of it, then $8 million is charged to the cap.
Also, why does it usually take so long for negotiations?
The player has to have some incentive to give up money. If they don't give up money, it's not a buyout. And if they don't give up money, the team has no incentive to waive them - they're stuck with paying the guy anyway, so they may as well keep him.
Secondly, what's the usual amount guaranteed on contracts
100%
and is their a site that shows stuff like that?
http://data.shamsports.com/content/page ... /index.jsp