In my game artifacts attune (think samurai swords) to the characters and the skill attunement replaces use magic device. As the characters level and when they acquire items they make attunement checks and when they achieve something the artifact develops new abilities. This gets rid of the world of disposable magic items. Small stuff, potions, scrolls, etc don't get this ability. This allows characters to work with the GM to theme items. Such items ultimately have some limits set secretly by the GM based on the power capacity of the item.
I like the idea of different weapons being suitable for different parts of the fight. That adds flavor. I would say you should consider different fighting styles in the way you have for monks. Anything that takes the players away from, "I attack again, I roll my die, I hit, I do this much damage, my turn is done" as opposed to, "I lunge forward in the dragon form, smashing my shield into the intervening goblins face to knock him aside, then plunge my glowing blade deep into chest of the orc behind him, driving him stumbling back into his companions while shouting, 'For The Light!'. So dragon form stance, lunge, shield bash, thrust and intimidate could be a preperation feat, 3 types of attack action and a reaction. Add as much flavor as you can to the mechanics of the combat and the fighters will come alive. So more weapons, more descriptions, more situations, more movement. Real melee combat is fluid and chaotic, not generally repetitive except in specialized situations. The feats and tactics of fighters should support that dynamism instead of encouraging them to stand in one place so they can make the most attacks to generate the most damage.
Yes I think you're on the right track with this. Each level should feel significant to all classes. Each level should give you new abilities. They can be small, specific and nuanced for purposes of play balance but they should be there. One of the worst parts of 3.5 that Pathfinder has improved upon was dead levels where all you get is hit points. Pathfinder improved that but still could do a lot more. Just getting new spell slots by the way should not count as what you get for a level. That is about as exciting as mud. And I'd do away with the experience. It's never used in the games I run or play in. We're telling stories, stories break into chapters and characters should level at chapters. They all need to level together btw, having characters at different levels is a terrible gaming experience for the stragglers.
Wrong direction on this one I think. The bonuses feel mediocre and the descriptions vague.
Here's a suggestion I was considering for a game of my own. Keep the bonuses based on ranks but roll an extra die for each tier of proficiency. Player keeps the best die. Much more exciting then and an additional +1.
Also each tier in something should give you something cool and defined and new you can do. Preferably open a tree of actions.