Just found and finished reading your thread.
Looking good so far. I planned my tank for 3 years before upgrading.
Guess you can use this time to start buying stuff that you know will not be old technology by the time you do the tank. maybe buy the tank and keep it aside that would be a good temptation to make more savings and buy more stuff and you'll find yourself starting on it earlier than expected.
For lighting I would still do MH and supplement with T5. My final plan for my tank is 2 150 MH on the sides 1 250 in the middle with actinics and 2 T5, but that's a 150.
On which size you should do, I'm already wishing I had a 200 and I even don't have fish and corals in my tank yet so I would say go with the biggest tank possible from the start.
One thing I would worry about is flying balls from your Pool, I read somwhere that you can use a very thick curtain that drops in front of the tank at certain distance from it to stop any flying ball.
Good luck with starting it and tagging along.