couple of comments:
1 1/2 deck screw for the first course? are you sure ? for hw floor, use nail gun for the first course on the face of the board and on the tongue of the other couple of courses until you can use the regular floor nailer/stapler. use the special putty with maching color to patch the holes on the finished surface afterwards.
also 1/2 to 3/4 inch is way too much gap, you will not be able to cover it up with the baseboard/quarter round unless you use the bigger profile ones. as long as you open up the package 72 hours and leave it in your house prior to installation, the boards are fine. 1/4 inch is more than enough
45 degree is not recommended: 1, no room are square, for the same reason, no room are perfectly 45 degree. you will have hard time at the corners. 2, i saw your miter saw pic, it is not that powerful for this kind of job- it is okay for plumb cut with a new fine teeth blade, but not for miter cut. when you use that to cut your 45, the blade will drag the piece into it and most likely you will get a curvy cut rather than a straight one. I use a bosch 12" 15 amp miter, around 700 bucks, still have hard time sometimes when the wood is hard or in a funny angle.
last, make an estimation of how many courses you need to finish a room, do not wait till the end of the job and you find that you need some 1/8" pieces to cover up. thin pcs are really hard to cut with a table saw.
hope that helps