Hello there!!
Welcome!
1. It already is
2. Yes, they are completly compatible. LoTR = The Hobbit
3. Well let's see... The last wave I can remember was:
Easterling katerphracts
Great beast of gorgoroth
watcher in the water
Easterling dragon knight
Amdur
Groblog, king of the deeps
Ashrak
Warg marauder
Casualties
Rohan, Gondor, Dwarven and Galadhrim commander packs
Dwaller in the dark
5 new army books
and also a new finecast fellowship (mines of moria version)
And also everything in the Hobbit range
Also, the deployment and structural system of the game has been changed. Now armies consist of warbands. Each warband consists of 1 hero leading up to 12 warriors (all of which must be from the same faction (ie Faramir leading 12 Knights of minas tirith would be a legit warband))
I hope this helps
If you have any more questions just shout