1) is it possible to get any STD from a handjob with a little saliva used as lubricant?
No
2) is it possible to get any std from the towel or sheet if it was dirty? They claim to change after every person
No
3) would and std show up hours after exposure? Or is it likely my penis is just inflamed due to the vigorous handjob?
STIs take days rather than hours to show. But a vigorous hand job can cause friction, inflammation and discomfort which settles with time.