Is it the book by Chandra Beale you're looking at getting? It's sort of stick drawings and stuff but it's pretty good. I have had particular success with it on aggressive or frightened bunnies, it does seem to make a difference. As with all these things, there's a lot of trial and error but I do find the techniques a useful starting point to work out what your bunny likes. I think Chandra has a DVD as well but I haven't seen it
Hmmmm...to be honest I wouldn't believe a word that someone from a freecycle type site says. In my experience (and that of many rescues) they'll tell you whatever they think you want to hear as long as it means you take their animal off their hands! It's highly unlikely you'd get the sort of owner who would spay a rabbit, giving it away on a site like that.
Personally I would suggest seeing if your vet can do an ultrasound to check if she is spayed and then do the op if they aren't sure...I may well be wrong but I would lay money on a female freecycle type bun which displays aggression being unspayed.