Borrow a lens from someone or go buy one. If you can't do that and are concerned about seller integrity, buy your GH2 from someone who's been active in the personal-view.com community. I'm sure a few guys are selling - you can search the site or even post a WTB for a GH2. I would recommend that over CL. Good luck.

Yes - if it's working I'm not sure what else could be wrong, but of course you ideally need to be able to put a card in it and test it out to make sure the sensor or card slot hasn't been damaged - either of which I guess you could test without a lens. If it were on ebay with a seller with good feedback I would be pretty happy to trust buying a used GH2. I don't know what CL is but assuming it's some sort of online sales thing, it should have a reliable feedback mechanism you can trust, so you have a come-back if something isn't right. I'm assuming it comes with an original battery otherwise that's another expense.

CL is CraigsList, which can be fine, but can be a bit iffy at times.

I think it will still show a full (but black) display if turned on with just a lens cover. I've owned 3 gh2's and used the hell out of them. The only thing that ever broke was the SD card slot, it no longer clicks into place with an inserted SD card, however the little SD card door nonetheless holds the SD card in place and it works perfectly. Look at threads on the lens mount too. Look for obvious water damage/physical trauma to body.