1) It will be almost identical.  Rates of learning O/D are all very close.

2)  By far.  All that the lower GPA means is that you need more SH minutes.  In this case with a 2.00 HS GPA you might need to start him out with as many as 25 to 30 SH minutes.  With a 75 WE vs. a 25 he should still grow appreciably more quickly with that many less practice minutes, so all other things being equal I definitely take guy #2.  I barely even look at GPA anymore.

the 3.00 / 25 WE will improve about 20% slower than the "normal" player (3.00/50 WE).  Meaning by the end of the 4th season he'll be almost a full season behind.

1) Probably, and it matters, but not a large difference in change. Not like a 3.9 vs. 2.1... I've seen a chart somewhere in the forums (iguana?) where a coach lists probable impacts of H.S. gpa. The only surefire way I know of to learn how fast a player increases IQ is evaluations during recruiting. You'll get a "Fast/slow/avg" learner comment. Also, note that no matter how good his college grades may become his fundamental ability to increase IQ will not change.

2) YES. (well, 99.9%, I suppose the "not smart kid" could be the worse student in the land and require 30 minutes of studyhall, still become ineligible with a 1.9gpa at end of term, and just generally cause stomach acid to boil.

In general, do factor in hs gpa. I dont search for it during recruiting but do use it to compare between the players I've found.