Making up new windows

I am pretty amatuer (but slow and careful) and would appreciate some advice from the more experienced people here.
I am replacing a couple of windows in an old house that are beyond repair. I have managed to save the frames but the windows themselves are gonners. My questions are:
1. What timber should I use for the new windows, I have had cedar and treated pine suggested. They will be painted, so appearance is not important. I would like to keep cost down, as I will never turn this into a showpiece without ripping out the whole bay window and starting again (not on at present). But I still dont like to do a cr*ppy job.
2. How to make strong enough joints? I do have a router, and can drill dowell joints, but dont have a biscuit joiner or other fancy joinery tools. Will dowel and glue plus long screws through do it?
3. I intend to buy plain 68 x 22 timber and rout out a rebate for the glass, as the timber yard I spoke to did not have pre-shaped window frame timber. Are there pre-shaped profiles generally available?
4. I may be getting out of my depth here but I also thought of including a couple of panels of different colours. Any leads on a thread or website on making up the separater battens would help me decide whether to try that.
Any other tips would be appreciated. Thanks in anticipation.
Peter