#1
I recently realized that there is a very old Mandolin (no brand anywhere, but there is a church on the back of it) made somewhere in eastern Europe, most likely Ukraine. Is it difficult to play compared to Acoustic? How do you restring it? and most importantly, what strings are market standard to have a good starting point for a complete Mando beginner?
#2
Mandolin strings are generally available and in gauges just like guitar strings. Re-stringing is a bit tedious (there's 8, after all) but not difficult. Go to the Frets. Com site (for some reason It won't open for me right now)
And look at the "of interest to musicians" section and you'll find the Mandolin restringing clinic.

Be aware that if the instrument is indeed "very old", it may be wise to have a luthier look it over so that you can be assured that it will take the stress of new strings and that it doesn't need repair.

For all things Mandolin related, go to the Mandolin Cafe site:

http://www.mandolincafe.com/

Where you can find tabs, instructions, chord charts, a forum... All that stuff.