"Executes onto bombsite are gonna be nuts, the amount of fakes and tricks you could do to make people believe there’s a full execute coming your way" yeah, literally 0 unless it's MM against gold novas. All smokes are thrown from different positions so CTs will notice delay between them, same with flashes/molos. You can only use it in a situation when u go normal execute with like 3/4 ppl, u throw nades with a little bit delay so CTs think it's a 1/2 man fake but there is a full team.
Yes, there is a limit of how many nades u can buy, they didn't change that. U can buy 1 smoke, 1 molo, 1 nade and not sure about flashes tho.
It will be used only when 1 or 2 ppl have shit tons of money and rest of the team barelly can buy a weapon + kevlar. Or when u want to stack one site and leave one guy on another, like on B inferno where u can leave him alone with some utility in safe spot to pick up.