real capacity of one routerboarb 532a

Hardware MikroTik hardware general
1

whichever wireless clients support:

1 RB 532a Older Revisions to 266 mhz + 1 SR2 with PoE 48 w
1 RB 532a Older Revisions to 266 mhz + 2 SR2 with PoE 48 w

I can raise to the speed of the processor of the RB 532a
whichever clients recommend to me by minipci SR2?

2

Yes, you may try to overclock CPU frequency to higher, login to the RouterBOARD BIOS to see supproted frequencies and try them.
I think you may use any client that supports 2.4GHz b/g.