TRAVEL: It is possible to made a journey from Crimea through Abkhasia to Tbilisi?

My friend - the filmmaker Sebastian Kaiser - is planing to go this summer from Crimea (Ukraine) somehow to Georgia, Tblissi.

For me it´s clear how to go to Sotshi (Russia). But I have no clue how to reach Tblissi from Sotshi? Do anyone have an idea how to go with a German passport from Sotshi to Tblissi?

I have three concrete questions:
1) Is it possible for me with a German passport to enter Abkhazia? Do I need a visa and if yes, which one? Is a Russian visa enough or does there exist a special Abkhazian-visa; if yes, where can I get it? At the border or somewhere in an embassy?
2) Is there a direct train or bus from Suchumi to Tblissi?
3) In case it should´nt be possible to go to Tblissi via Abkhazia, do you know if there exist a train which goes from Sotshi (or somehhow Russia) directly to Georgia without passing Abkhazia? For instance via Vladikavkaz?

I really appreaciate every information you can provide me concerning that Caucasian
issue!

Thanks for your help!
Many greetings from Berlin
Sebastian

Contakt: skaberlin@web.de
His homepage: www.balaklava-odyssey.com