While not a 3E/PF fan, I decided to check it out. There are many very interesting ideas here, some of which I may steal for my 5E game. Some of them I like, but won't use (like the 3 actions per turn) because of some baked in notions I don't like (move actions). Others, like the bulk encumbrance system, are gold (may need some tweaks).
One thing that baffles me is the proficiency system. In a system where you add your level to your roll, the difference between a trained person and a legendary master is a +3 modifier? The difference between untrained and trained is moderately significant (-2 vs. +0), so I would think they would continue the +2 for each step, making the difference between the training levels more meaningful.
Also, adding proficiency to AC in addition to armor and shield is likely going to create a system at mid to high levels where most attacks will miss. Assuming even leveled/trained/equipped opponents, assuming they wear the optimal armor for their dex (making the AC modifier +7), an 18 Str attacker will have a 60% miss chance. A large shield pushes this up to a 70% miss chance. If high variable combat is their goal, where infrequent hits deal significant damage, this would work very well. However, IME most players prefer to hit more frequently, even if the impact of the hit isn't as great.