Mounting my PCB project
I'd probably go for M3 or M4 stainless steel socket head cap screws. They're strong, corrosion resistant, and readily available around the world. If you google DIN 912 A4, (DIN 912 meaning a metric socket head cap screw and A4 meaning stainless steel), you'll find lots of suppliers.

One such supplier: http://www.mcmaster.com/#din-912-a4-socket-head-cap-screws/

I'd have those screws pass through nylon unthreaded standoffs and thread into whatever you're mounting the board to. Here's what I'm talking about: http://www.mcmaster.com/#catalog/116/3240/

You might also try snap-on plastic standoffs like these: http://www.mcmaster.com/#catalog/116/3245/

They're designed to snap into a 5/32" (3.97 mm) hole, so they should just fit.