Probably in your case you probably wont need a shotgun mic. They are definately needed in the big film studios where there is tons of noise from equipment and people talking while the film is shooting. Because normally around 90% of the vocals done on film are overdubbed, what is generally required is just so the actor can hear his voice without excessive noise in the background so he can do his overdubs successfully. In your case, almost any condensor mic will do quite well. Ive used the MXL603s on a boom like that before. They pick up a generally good sound but can be a bit noisy for that purpose, especially if you use the stock windscreen outside, that thing sucks. I actually use the SP C1 as an overhead in films, it has a great sound but it is damn heavy. The main reason i chose this mic though is because it comes with a big fat windscreen which works pretty well, and im not afraid of dropping it because its only $200.
As far as the Fishpole boom, you could easily spend around $400 on one. But you could also spend about $20 and rig one with a painters extension. I have not done this yet, but i have heard of it being done. The the painters extension is great, but the threads on the end do not fit a microphone, so you would have to rig it. If you end up doing this please let me know how you rigged the end of it to fit a microphone on their. Get a nice paintors extention too, like a fiberglass one, not a wood one. And get one that is size adjustable.
danny