I have seen the 6 page illustration on working on stairs as well as doing many searches through out the posts within this forum regarding stairs and nosing.
But I am still having some questions that maybe I missed the points on other threads. So I am sorry in advance if these questions sound simple.

My present stairs were covered with carpet which now have been removed. I have enclosed stairs with exposed stringers (top of stringer and inside of stringer are exposed) and am doing 3/4 inch pre-finished Maple floors that are 3.25 inches wide.

Questions:

Risers:

1- What is the common practice here? Should I use the pre-finished flooring for my risers (this would be simple since they are pre-finished) or should I get some Maple plywood (high grade), stain it to match and cut the risers for each stair?

Stringers:

2- How would I finish the stringer top and sides off (they are exposed and are made of a 2x12 or 2x10)? I seen stairs at a friends place where they took some oak plywood stained it to match and made a heavy paper template for the entire run of the inside stringer then cut it out in one piece and applied it (this might be tough to get that total tight finished look). Then the installers ripped a 3/4 inch piece of cabinet grade oak plywood stained to match and made their own trim with a routered edge to cap off the top of the stringer.
Does this sound like the way to do this? It will take a lot more time but the final look was spetacular.

Overall Stair Work:

3- I plan to do my stairs in the following process (there seems to be various ways to do this process).....
Apply the inside stringer covers first (whether is be sheeting stained to match or actual flooring).....Then I will place the first board closest to the existing riser with tongue outward and face nail it so the riser hides these nails. Then blind nail through the tongue (these boards will also be glued down as well) Do this until we get to the stair nose where I will then glue the stair nosing and then face nail the stair nosing (two nails per end and two in the middle) then applying wood filler to cover the nail holes. I believe this is the way Floorguy suggested to do it in another thread and makes the most sense to me as I can then blind nail all the boards except the stair nose.

Are there better ways to do the stair nosing without the face nailing? I plan on using Bostiks adhesive.

Does all this make sense in the way I am approaching it, or is there better ways?

#1) Either way, your choice. It maybe hard to match your flooring exactly if using maple plywood. Another option is paint grade wood. You can use MDF, poplar, paint grade plywood, etc. and no concern about matching the flooring.

#2) It can be done this way. It is sorta like cabinet refacing as you are veneering over that rough framing lumber. But in the correct sequence of events, one would install the stringer/skirt veneers first before installing the treads. This way, you only need to be about 1/2" within your measurements so it's much easier. The flooring will but cut net and tight and will cover any gaps. You could also use paint grade stock as well. Or sand, prime and paint those rough framing members. With some sanding and filling and proper priming, they may look OK for paint. You can cap off the top with anything that looks good to you.

#3)
I would'nt try to use flooring to install on your stringers. That will look just plain weird and be hard to pull off..When installing the flooring on the steps, carefully measure how much the flooring will need to be ripped. It always needs to be ripped down. And install the first ripped piece up against the riser, tongue facing out. If you're gluing, no need to face nail unless you want to. Also, if you're gluing, just nail enough to secure the boards untill the adhesive sets and cures (24 hours) Now if you measured accurately, the last board will be a full board and the groove of the nosing piece will engage the tongue. I apply a little carpenter's glue in that groove and glue the nosing down to the tread as well. Then a few well placed headless brads just to secure it untill the glue dries well. This way, very little puttying is needed and the adhesive is stronger than nails anyway, most of the time.