Hi Dave,
If you can snatch up a 2226 for good price, you'll fall in love with it. low, med, or high volume. It's just a great all around driver and it's clean and pure.
The Deltalite should be a great driver for your arrangment. I am wanting to do the same thing when time permits. The 4540nd crossed over at 2.2 is perfect. I have been more partial to an MMT instead of the MTM. Either way should be good.
You'll need a pair of the 10" because the sensetivity on the 10 is less than you would like. I would wire them in parallel so you have a 4ohm woofer.
Tubes? hard for me to say. in most cases a true 8ohm load might be better for 'most' amps, as a generalized statement. Using a 4ohm load for a woofer with a passive crossover and an 8ohm load for the tweeter is not as harsh a scenario as a true 4ohm designed speaker.
Bill