I have the same grinder, it works good but unscrewing the bottom layer is pretty hard. Mine got stuck and wouldn't twist either way so I had to bash it on the table to snap it on, but it works fine now.

Pipe looks like it's high quality and heavy glass, looks like it'll last. I'd wash it just because you got it from a flea market so you never know. For cleaning the resin, use Slip's guide if you wanna smoke it but if you don't, put it in a baggy and add enough rubbing alchohol to get it under, and a little salt and shake. Make sure to wash it out with hot water, and then scrape what you can get, then shake it in the bag again.