It was also said that a creature CR 5 with 10 Mythic levels would not be as effective as a CR 15 because it would still have a CR 5 AC, BAB and Damage.

This sounds a bit like Benjamin Durbin's (Bad Axe Games) work on the "The Spine" for his monster tweaking in Trailblazer (3.75) game...

...so...how exactly does the Incutilis Puppetmaster Special Attack work? I don't see poison in the stat block, and the jumps on you and instantly kills you attack seems a mite powerful :P

ok then, my First House Rule: starting racial hit points

To be as polite as possible I will answer as simply as possible.

No on all accounts.

agreed!

I let anything go if adequately explained in a backstory and then make some feat which makes it so...I especially like Weapon Proficiency (Improvised Weapons)!

I can't wait for the Pathfinder gun rules - can you say Gun Kata?