You could make them through a travel/marketing agency other than RailEurope such as Budget European Travel Service. All of these agencies use the same computer system that RailEurope uses (and be aware that RailEurope is the North American marketing arm of a combination of the French and Swiss National rail systems).

I would at least call another agency and ask about the possibilities.

Yes, you will pay fees unless you can access the rail systems of either Austria or Poland and do it that way OR try using the Germanrail site www.bahn.de but you might end up having to call them and do it by phone.

I don;t think passes cover compartments in overnight trains - I think they must be bought separately. Have a look at the rules and regs of your pass - if you've already bought one. And I would assume that 2 people in a compartment is first class - so unless you have bought that - don;t know how it would be priced.)

For info on specific trains - go to bahn.de and it will list all trains/schedules - althouhg it provides prices only for trains starting in Germany.

Passes do NOT cover reservations in sleeping cars. On some trains you will get a passholder discount on some sleeping accommodations but that I have ever heard of you will not get that accommodation as the result of having a pass alone.

As noted, your railpass doesn't cover a sleeper. You must purchase sleeper reservations separately.