first tfp shoot-advice?

[Osmer_Toby]

i will be working with a single speedotron, a soft box, two 550ex's with a variety of umbrellas, a 420 ex if needed. i can shoot both digital and film, alas, both 35mm, no mf. have never worked with a professional before.
so, my questions:
a) should i use a written agreement of some kind (i know this is a yes- but any details?)
b) should i use only one lighting arrangement and stick with it?
c) what other decisions need to be made prior to the shoot and who makes them?

the model i'll be working with responded to a group email i sent to an area modeling website for photographers and models. actually, i haven't even responded to her response, yet. don't want to sound like too much of an idiot, so i thought i'd try to get some input here. i'll need to respond sometime soon...