oil change questions

[bluehose2012]

hi, I've been reading through posts about changing oil and filter.

should I use regular or synthetic oil? 10W-40? motorcycle specific?

what filter does it take? can I get one at a local auto parts place or online?

I'm changing it because it looks pretty black. I bought the bike used, and the guy said he recently changed it but not the filter. I've gone about 1000 miles since getting the bike, and I just want to be on the safe side.

any other thoughts or input? thanks so much.