Regarding wheels and hub spacing: read the
Sheldon Brown article on frame sizing, specifically the section on "Frame Spacing Adjustment."
Your current biking likely has 126mm rear hub spacing, and 8,9,and 10 speed hubs have a 130mm spacing. Read the article to help you figure out if its possible to get your bike to work with an 8 speed hub.
Other than that, your list looks pretty good. Good luck with your build, going from downtube shifters to brifters is a huge jump in ease of riding.