Yes and yes. You can essentially use any 3rd generation Core-based socketed laptop processors, codenamed Ivy Bridge. (Theoretically Sandy Bridge would work too but there's no sense in going backward a generation) Here's a comprehensive list of all the potential upgrades you could do:
Celeron 1005M
Celeron 1020M
Pentium 2020M
Pentium 2030M
Core i3-3110M
Core i3-3120M
Core i3-3130M
Core i5-3210M
Core i5-3230M
Core i5-3320M
Core i5-3340M
Core i5-3360M
Core i5-3380M
Core i7-3520M
Core i7-3540M
Core i7-3612QM
Core i7-3632QM
The only options that have more cores are the QM i7's at the end, although every processor starting from the i3's have 4 "virtual cores" (or threads) powered by 2 actual cores, so you'll still get a performance benefit...