what can I do to reduce this time?
Computers are also designed to run 24/7 and weekly or monthly reboots depending on your usage is really all that is needed. I just turn off my monitors. There is actually more stress placed on the system by booting and shutting down every day. Also at idle very little power is used so your electricity bill won't be outrageous. I have always run my systems 24/7 and never had an issue.
Windows 8, 8.1 and windows 10 official Iso's are all UEFI compatible, Winodws 7 i'm not sure but with an NVMe driver from samsung it should be bootable as well
Does this means, that i wont be able to install Windows 10 from the Microsoft USB Pen in UEFI?