I'm currently learning guitar.A few months ago i watched a singing show call "xin guang bang" and there's a guy in it call"xiao jin teng" , his way of singing and playing of keyboard has influence me.He's using Yamaha PSR-S500 which i think is too exp and not suitable for me. And now, i would like to get a keyboard for self learning at home.
i'm isn't poor nor rich.so my budget is around rm 200-rm300 only.

I don't know anything about piano so hope anyone can tell me ...
whats the different between 49 ,61, 76, 88 keys ?
whats the dif between midi keyboard and portable keyboard ?
which one should i get ?

Thanx