Here's my opinion regarding your questions.
The chassis within brands are usually very similar in sizing, so they should fit the same between models.
The answer should be no unless you are cramming your boots into the binding or the boots were hurting your feet to begin with. You don't want too much space between your binding sides and the boots.
It shouldn't be an issue. I have the same problem with my Targas. The only issue is that it's a bit of a PITA to get the ladder locked in sometimes. If possible, you should see if you can get longer ladders. It'll make your life easier.
Thanks yeah the boot just fits in with no space widthwise, no cramming necessary.
Where would I obtain longer ladders? Would that have to be from Ride/K2 or are toe ladders usually interchangeable?