Are they scanning finger prints today??

Yes they are

They started scanning finger prints so multiple people can't use a single pass, since no one has the same finger print

Yes

They added fingerprints to season passes a while ago. But they don't always check them. And some days, one person will scan them, but another won't. Just depends on the person I think.

Can you use 2017 pass for 2018?

Yes they should be

I didn't know that they scanned fingerprints... Great question