Router RB1100 or pc with RouterOS - hotspot(wisp) - outdoor

i have a question regarding the routerboard: Router RB1100 - 13 Gigabit Ethernet 512MB 800 MHz L6 (rack)
future config:
on the roof i wanna install 9 antenna, 3 x 2,4gHz, 3 x 5gHz for clients + 3 x 5ghz for my expantion posts in town.
9 —> switch —> long cable —> office into Router RB1100.

can this be configured?

i mean those 3 antennas for expantions are not affected by username and paswords, but direct links to other expantion wifispot owned by me, which will have the same setup, 3 x 2.4gHz and 3 x 5gHz + a 5gHz link back to the office.

i supossed it can, but i wanna make sure as i’m new to the subject, i read
http://www.mikrotik.com/pdf/what_is_routeros.pdf
and saw some video on youtube

is a RB1100 better than for example a core i3 powered pc?
the benefit i see, the RB1100 doesn’t need a monitor, but it only 800mhz.
on a pc based system, buy a pc, buy a monitor, keyboard, etc, etc, but … it can have more ram.

i’m aiming for something between 250 and 500 users.
assuming … having level6 installed it’s capapble of handeling that traffic.

pc or routerboard?
i would some advice form you guys.
thankx