I don't care about the traffic and the quality of content as long as the site is in all major search engines as has been there for more than a year.
I'm sure there are tonns of people who abandon their smalle personal sites each and every day. Is there a place that brokers domains like that? Before the domains are deleted or the content is removed?
will you lose anything (backlinks, ranking etc.) by transfering them to you?
My understanding is that Google will 'reset' your ranking when they realise that the owner of the domain has changed. Quite how long that would take is another matter.
I'd guess that the majority of back links would remain as people do not always check them - and then they would only be removed if the content changed - for example a DMOZ link may be removed if the content was no longer valid and it was spotted by an editor or reported.
My understanding is that Google will 'reset' your ranking when they realise that the owner of the domain has changed. Quite how long that would take is another matter.
You will only lose backlinks/ranking if the domain actually expires. If you purchase an active domain and gradually change/add content it will be ok. However, I wouldn't go changing the theme of the site significantly just incase google detect and penalise this sort of tactic.
Does google check the registrant's data?
From what i've seen not yet but i'm sure it's only a matter of time.