Someone offer me a reseller plan. What can I do with it??? If I sell smaller packages for others, will they have full functions like other normal package, I mean CPanel, POP email, domain host... etc?

Generally yes, they'd have functions like other normal package. It depends on the exact reseller plan you're signing up for, and everyting else, and I'm sure there are reseller plans which don't offer everything but ask the provider to be sure.