I'd go with web address B as most people say "One eight hundred"... I think they'd type it in the name. I don't think anyone would type the dashes so I'd avoid those.
I prefer logo A. The .com is more visible giving the dual meaning (website and phone number) more clearly.
BUT - it's not an either-or thing. Whichever one the user types in, they can both resolve to the same site. Or to a 3rd site that's named something completely different. So pick the one that you think is better for your marketing but know that you've got them both (and maybe others) in the Big Net.
I think the logo with the green box is snappier and more memorable. With both scrolled off the top of the page for the last 90 seconds where I can't see them, I don't remember what the non-green logo looks like.
I like 1800sell4cash.com but I'm sure you will use both and have one redirect. I like logo A the best by far because of the green house. A lot more POP.
logo B there's reason people don't remember it. They accept it. Add the website in underneath the logo on a business card etc because even if it looks like people should get it - someone won't.