Since you're location isn't listed feel free to disregard what I'm about to type as it may not apply to you (especially if you're in the southern hemisphere). Breeding season (as much as there is one) is ramping up now, so this will be the most expensive time of year to buy an adult female (a lesson I learned the hard way first hand). If you wait until late spring/early summer you can usually find a good deal on a female who has just laid and just needs a few months of steady feeding (and qt!) to get back up to breeding size.
I highly recommend perusing the big morph list and genetic wizard at worldofballpythons.com. Find something that "speaks" to you (was the axanthic bee/killerbee and axanthic super pastel for me) and then figure out what genetic options you have to get from A to B (and figure out your budget). When you keep going back to look at picks of the same morph on the list over and over, that may be "the one."
As far as your incubation question goes, it depends a lot on your local climate and personal preferences. I live in AZ so I just have no possible way to keep the eggs humid enough for maternal incubation. But I'm also kind of a control freak, so I would probably go for mechanical incubation anyway (plus you can get mom eating again much sooner). Hope this helps!