Re: Is it possible to connect external switches to dsPIC starter kit DM330011?
J2-4 are not mentioned in the docs, nor shown in the schematics.
J2 looks like the ICSP connector required for factory programming of the PIC18, so I would leave this one untouched.
I didn't bother to analyze J3 and J4 in detail. As the traces are visible, put a bit of work into it and check where the traces go to. This can be expected from an EE student.
PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)