If your staying at the Rila take some filp flops if you want to use the pool. They don't let you in pool area without them. You can buy them for 10Lev out there.
A beard is good, it was -28 when we were there, Mike my husband skied down from the top, when he got to the bottom his face was white - his beard had frozen - he tells me it was good protection. At least now I know what he'll look like when he's old.!!!!!!!