I am a 16 year old aspiring engineer with 7 years of experience in cad software specializing in onshape. I was bored one day and wanted to see if i could make myself some custom keycaps so I did I encourage you to try and make your own keycaps with the standard keycap as a template, but I can add more upon request

Doesn't Matter

Yes

for stronger keycaps print them upside down with supports as they are easier to remove and the layer lines don't travel at the same angle as the flex tabs or you can print it flat with custom supports around the bottom i recommend slim tree supports as they come off clean but using this print orientation risks the key snapping under stress as the flex tabs are decently thin