With both of these questions, the answer is probably to try before you buy...
Most tall people are OK on a 16in western saddle, but if you have very long legs you may need a bigger saddle - different seat shapes can also affect how the saddle fits you.
Boots are pretty random - USA sizes are usually one bigger than UK (sorry not sure about European sizes!) but can be two bigger (Ariat). My other half actually takes different sizes in Ariat, Laredo and Justin boots...not much help!
If you can get to some shows where there are western tack stalls (not sure what the show scene in Bulgaria is like...) you could try different makes of saddle and boot.
Hope this is vaguely hopeful