Yes. There's also be quite a few Catholics if you were willing to marry someone from one of the minor states. Re grand matches however, I think suitable Catholics were thin on the ground during this particular period.
That's much better than a German nobody, IMO, and the Princess is well connected.
I agree. Francisca Josefa of Portugal would be a good choice - continuing an important alliance and hopefully bringing quite a bit of money into the country too. I don't think the age gap would be viewed as a problem - the more years she has to be fertile the better! Also Frederick, Prince of Wales (son of George II) was about 12 years older than his wife Augusta of Saxe Gotha Altenbourg who was only about 16 when she arrived in the UK so I don't think anyone would mind about Francisca's youth.