now you always hear that blind people have improved senses (hearing touch and smell) should they get a - 1 or -2 to perception tests involving such senses like the ghouls?

ghouls by the way have -2 to hearing and smell based tests.

Only if they pay for an Edge that provides that bonus, IMO.

I'd say that's more a by-product of their ghoul-ness than compensation for loss of vision. Normal PC's only get a bonus if they pay for them as edges IMO.

Blind people don't really have improved senses. It's just that sighted people don't bother paying attention to their other senses. Blind people kinda have to.