Hi matt,
I am no expert but here is my take on things
On the rod front, #2 or #3 line. Well...it used to be said that if a rod had 2 ratings on it, such as 2/3 then it meant a DT 2 or a WF3...which leads onto your next question
DT or WF...a lot depends on the river and distances you are casting...and how you are casting. If its a small, intimate river, then you will probably want to overline your rod with a DT line. So, instead of a 2, use a 3 or a 4. What this does is load your rod with less line in the air and thus allows you to make easier short casts.
However, if you are good at casting and can perform underhand, spey or similar casts with a single handed rod, then a WF line can be shot easier for longer casts, even though you may have trees and high banks behind you. Some anglers I know use a very short head in such circumstances, but can still shoot 20 yards easily, more if need be.
If the river is wide and open, then a WF line can be better for overhead casts, but harder to "mend" if needed.
As for rod length, I would say if you are in a boat "dibbling" flies in front "loch style", then an 11 footer is ideal. If you are on the bank and casting distance, then a 10 foot or even better, a 9 foot 6" would do it. I have an 11 foot 8/9 weight and its murder on my wrist if fishing for any length of time. Normally on a big reservoir I use a 10 foot 7/8 weight with a WF8 line is wanting distance.
Others may have different takes on what i have said..but hopefully I have put down the basics for you,
Regards
Rob