3. The 182 is much faster than most training aircraft. The controls are also heavy and things happen a lot faster. That might extend your training as others have already noted.
I don't agree. Comparing a 182S to a 172P ('cause those are the two most recent flight manuals I have for the types), the 182 is only 3 knots faster for most speeds slower than "normal" climb, and indeed 1 knot slower for short field approach.
I suggest that a 172 flown heavy will feel more heavy than a 182 with a similar load, but yes, a fully laden 182 will feel a little more heavy that a 172.
With cowl flaps, and assuming their appropriate use, the 182 will be just fine for PFL's, and will indeed overshoot with much more confidence.
A pilot who completes PPL training on a 182 would be just fine, with perhaps an additional hour or so added incrementally while propeller and cowl flaps are properly learned, but that is a valuable skill. A 182 trained pilot might be less confident getting into a 152 on a gusty day, but other than that, and the greater cost to operate a 182, there is not reason not to learn in it.
As soon as I was permitted after PPL, I transitioned to the 177RG in the club fleet, and flew 50 hours on it - one of my most wise pilot choices in hind sight....
The "break" between "easy" and 'not so much" in the Cessna tricycle product line, for abinitio training, comes at the 100 to 200 break in my opinion.
The 182RG is a wonderful plane, but consider ownership with caution, there are some main gear parts, which if damaged, are very hard/scarce ($$$) to replace. The RG's are a lesson in speed management, but a lesson worth learning...