Stephen, you ideas are very good ones, and your way of thinking is good, as are your questions.
To answer them (as best I can):
1. Q- Is a 65 G tank harder or impossible to keep the temps/humidity up. A- Not impossible, YES LOTS harder. Glass doesnt hold heat well, and the screen tops most use for tank enclosures don't exactly hold humidity. As for the size, well, a lot of that will depend on the snake you get. For a hatchling BP, I would invest in a 10g setup also and keep him in there until he starts to get cramped. Most snakes prefer tighter smaller spaces, and so a 10g for a hatchling will actually help them to feel safer. You could also start out with a rubbermaid setup, which tend to make it much easier to maintain temps and humidity, for use while your snake is young. If at any time you decide to use the 65 g, make sure you have the "warm side" with a hot spot of 95 degrees, and keep the cool side at 80-85. You could accomplish this with strong enough radiant heat lighting, an undertank heater, or a combination of the two. Humidity can be increased by misting, providing a water source with a good surface area, and covering part of the screen top, as mentioned by Chris. Humid hides are another good idea! A 65 G tank isnt unsuitable, provided you provide a water source large enough for the snake to immerse himself completely and LOTS of hides spread through the tank, it should be fine.
2. Q- the handling thing. A- Well when you first get your snake you should leave it completely ALONE for 2 weeks and avoid spooking it if you can. Give it a chance to adjust to its new surroundings, and the smell of you and your home. I would still keep subsequent handlings short and infrequent. Chris's declaration of ABSOLUTELY FALSE or whatever is only one perspective. Its not about what is POSSIBLE, remember, but about what is BEST for your snake, who is in your care. Learn about snakes postures and what those can mean, and when you sense your snake has had enough, put him back. Remember that snakes don't show emotions like people do. We can't know if they WANT to play with us or not, but we suspect that most of the time, they don't really want too, but moreso are just tolerating our presence as they have come to trust us. Too much activity too fast will definitely freak your snake out, causing him to have bad sheds and making him more susceptible to diseases. Patience is key here. A lot of these factors will ultimately depend on the individual snake, and its own ability to adjust to things, too.
3. Q- Breeders local to Toronto? A- cant help you with this since I live in the states, but most of the breeders listed on the home page here also frequent the forums, and I believe are most all in Canada, so I would browse through those to see who is around.
4. Q- Keeping em together? A- NO! Most all species of snakes are solitary animals, and keeping them together increases your risk for cannibalism, as well as ensuring that if one of your snakes is ill, they all will be. Generally considered a VERY bad idea.
A couple of other things- Ball pythons being among the true constrictors will definitely destroy any plants or "arrangements" you would make in a terrarium style enclosure. If plants is something you would like in your BP setup, (and this is true for many other kinds of snakes, too) I would have to reccomend using sturdy silk plants. Easier to clean, also. If you ever have mites or something that you have to treat your snake and accessories for, then you could soak your plastic plants in a bleach solution, whereas terrarium would have to be totally redone.
Also- Look at the python regius forum for more BP specific stuff, and check out Matt Kameka's BP FAQ, should be one of the first threads in there..
Other species to consider would be Boas (non arboreal) and a cornsnake lacks the more difficult husbandry requirements, but they are much faster moving and can be "whippy" at first.
There are many others on here who may have slightly varied answers for your questions. I admit in advance I am by no means a "guru" on here, but the voices of experience usually know best, and it only takes a little extra effort of searching around on this site to figure out who those folks are generally considered to be.. For BP's in particular, you usually cant go wrong with any of the Mods, Jeff Favelle, invictus, mykee, Tim Cranwill, and a passel of others whose names arent leaping to mind at this late hour. If you get varied advice, its ultimately up to you to determine which is the best advice.
Hope this helps.. and good luck. Got a BP for my first snake and I love him
Artemis