I'd rather not see it made that easy in the game. In my opinion this is one of those areas where good players will distinguish themselves from other players.
You can currently either buy kegs, or play and use the gained resources to buy kegs or craft cards. I'd say that's fair. Using money to buy kegs only speeds up progress IMHO, it doesn't guarantee you will get good cards.
I've encountered bug #2 from the opening post as well. It would let me select other non-gold units, but not Geralt. Looks like a bug to me, because all witcher class cards are gold AFAIK.
I had the same issue with Promotion when I used it on Poor Infantry, once with two copies on the battlefield, once with four of them. But I've also had times where it worked.