New Titan Models also where to start?

Two questions today from a new epic player.

1. How do the new titan models for adeptus titanicus stack up with the old epic armageddon titans? I would like to use them as they look awesome but they look like they might be too big.

2. I bought 2 sprues of space marines and 1 sprue of the Ork Mob (planning on getting another 2 when I can) from the starter box on ebay is this enough for two small lists? what would be a good ork warband list and space marine list to run a 1000-1500 point demo game?