Lol good luck with using Qualcomm
1) hard to say as don’t know your house size or future plans for pool , AC etc
2) 14-50 you will be fine ...however you still need a 50a circuit which is half of what your panel is rated for ...ie what else do you have in panel (pic will help)
3) definitely HPWC if 2 electric cars unless you don’t mind switching plugs back and forth
4) I didn’t however my run is less than 3ft and I did to code ...ie correct conductor size ,load , conduit where needed ...height of HPWC from ground ...