The Art of Selling beats

[Bee-man]

I've put together some beats and showed them to a few MC's and now I'm getting request's for them to use on their albums.
Pretty cool huh?...I'm from the old school musician playing in a live band crowd,so this stuff is new to me.I gotta admit it's a nice alternative to the same old same though.

Well here is my problem.I don't know the ins and outs of these types of arrangements.A few questions to get the ball rolling.

1-What is or how do i find out what the going rate is per song i create?

2-Should i publish the beats before i sell them,so i can retain some song writing credits?

3-What is the appropriate method of "showing" the artist what i've got?..Should i bring my laptop and play the songs from there....i know better than to give them a cd of a bunch of beats for them to choose from

4-How long do you think i should make the sampler?...it's all done in midi.....so maybe 2mins including a chorus and bridge??

These are a few Q's i could think of.

Any advice would be great.