Me and a bunch of mates are just starting Epic together and I was going to go with Imperial Guard but then I saw the latest Adeptus Mechanicus data sheet and I liked it. So a few questions for any veteran Epic players.

1) What is the general play style/army composition of the Guard?

2) Are Adeptus armies any good, and roughly how should the army be constructed?

3) As the knight models are limited editions I can only find on eBay, is there any companies that make walkers that it would be OK to use as knight?