You cannot swap members between each other (
Swap Gate a few years ago was nasty affair

)
If you want someone who is on the draft list, you have to bid for them. Minium bids are of
$20,000.
When you make that bid you cannot withdraw it, you also have to state with the bid who you will drop if you win.
To outbid someone you have to bid at least $1,000 more.
To win a bidding war you have to go 48 hours without someone outbidding you.
Take
More Cowbell's current bid as an example. He bid
$20,000 for
Brett Dibiase and has said he will drop
Chris Masters is if he wins, that was @ 7.22 pm tuesday evening (UK time), so assuming nobody outbids him that goes threw same time Thursday night, the switch is automatic.
You wouldn't actually be able to drop
HBK as things stand, because in an effort to stop people helping others/wrecking their team for the fun of it, you cannot drop your #1 and #2 draft picks unless they are injured, released or don't appear on tv for 3 weeks or more.
As previously mentioned you also cannot drop your
TNA pick, you are stuck with them all game no matter what happens to them, hence the risk factor of picking one.
I think that covers it, all this should be in the first post.