1)
Your understanding is correct. Possessor's passive is a type of indirect passive, thus, 彼は国への貢献を認められた is a possessor's passive, and at the same time, an indirect passive, of course. I just wanted to point out that possessor's passive doesn't have a nuance of "that affected him", which 迷惑受身 has.
The reason why the passive voice is used here is to unify the subject of the two clauses. When the first clause is non-passive 貢献を認めて, the subject of it must be stated, such like 政府は彼の国への貢献を認め、彼はナイト爵位を与えられた. This sentence sounds a bit awkward. It's far natural to continue two clauses with the same topic.
2)
Yes.