this might sound a bit stupid but since i never collected my own pc from scratch i'm kinda off the topic right here. When i buy a motherboard does it come with the firmware or do i need to buy a firmware for it ?
The BIOS of the motherboard of course comes with the firmware installed already. Furthermore any firmware updates are free just as modern car software updates are free and cars come with the software for them to function. Drivers are also free. Everything else can be free if you know the Internet well.
You'll need to buy a copy of Windows.
Since Windows doesn't include Office, you need to buy Office if you want.
But as upstairs said, the drivers and applications will be inside the MB package as a CD.