How difficult is it to reclassify?

It is not, provided the MOS has available shots for your grade. When you reenlist ask if your eligible for reclass and look at what is offered. If what you want is not there there's also the commander's override list which will off a broader selection..good luck.

Depends on the strength levels of your grade and mos. Easier upon reenlistment.

I don't know if all states do it, but in AL and MA you can go to the HRO website and see what M-Day vacancies are available.