Need to start saying that im not familiar with shimano ok? (at least shimano 9 and 10 but yes with the old stuff).

If you go to sti 9 or 10 is for sure u might have to change the rd, the old rd wont travel enough and the cable pulling doubt will match the sti levers at all. I was you I would get d/t shifters and use them in friction mode, then u can use basically what ever u want, mix brands for example.

U can get wheels for 150 bucks at ebay for sure, shimano wheels are everywhere. CL is a good place but if a busted wheel goes for 150 better go new. If they last 3 years u got your money's worth big time.

If you are ok with your pedal choice just keep the same, dont see why u have to change it.

Good luck.