The ATMOS, I'm really not in a hurry on. It's just something I don't want to regret not being ready for. I really would like to stick with my next AVR for 6 years if possible

... hopeless right? On that note... cooling is really damn important to me, and service on an AVR. Fan grinding and such, and overheating... really not something I'm interested in dealing with on my next AVR, so I'd really like it to be able to handle more power than I regularly use. At least with my limited understanding of how these operate... I assume not driving a system to it's maxes that it's heat and fans will need to be worried about less.
Those Image T2 5-way towers, ... does anyone have an article on how frequency transitions in 3 and 5-ways like this, and what leads to or manages more precise and smoother transitions between the drivers? What roles do AVRs play in this from standard... to what more advanced AVR features have been seen with regard to it? Far as I can figure, my concerns are with frequency transitions, best speaker placement possible, and looking after reflection issues. I trust most other matters to these manufacturers for clarity and quality.
Between using towers for fronts, and bookshelf for surrounds if it's not too much to ask, are there any main caveats to proper configuration beyond placement? How unimportant is matching driver sizes with fronts to surrounds? Is the tweeter in the center what tends to me most critical for clear dialogue?
I hope these questions aren't too trying for you guys. I really hope with this thread to really stamp checks on any understandings I have and correct any misconceptions I may have before spending the money I technically don't have. If I'm jumping into debt, I want this baby to be perfect, and I hope to have it all configured minus the new AVR by May. Relocating to Western Canada, and it's important I start planning now in order to of course go house hunting and find place with an ideal room. Dream would be to setup the whole basement, and raise or remove walls if necessary.