Aminar, the only downside of your approach is that it seems to invalidate the social skills.  A particularly loquacious player with shitty deceit and rapport can still out-socialize a less adept player who invested points.  I'm not saying that it's a bad way to play, if you and your group like it more power to you.  On the other hand, if your less adept player says "I want to make him believe X," having him roll Deceit is not a role playing failure. 

EldritchFire: Their refresh rate, naturally. It's just instead of receiving your refresh rate every time you rest, have long down time, etc... They receive it only when circumstances are appropriate. In other words, if you're a slowly budding godling, instead of needing only a good night's rest and a little time to get fate back on your side, you have to actually act the part of your godly nature to wrestle destiny back into your own hands.

Do you really only get one action?
Or is it that you only get one ROLL?

Sure, you can have your character stand still, fire one bullet from his fully-automatic high-powered assault rifle, and call it a day (make a Guns attack against an enemy)...
...
OR...you can somersault over the heads of a dozen ghouls, your assault rifle blazing, kick off the wall of the alley they're likely now cowering in, and land, triumphant, on the roof of the building opposite (zone-wide spray attack against an adjacent zone modified by athletics with a supplemental action to move to a third zone adjacent to the other two - overcoming a significant barrier, no doubt)

I would rule that a player is not allowed to invoke aspects at any time they want to in a conflict. By this I mean, without any real support in the rules, that one side first invokes all the aspects that he or she wants, and then locks the results. After that the other side does the same. In case of an attack, the attacker starts, and then locks the results. After that the defender rolls and locks the results. A conflict can be seen, from the “attackers” point-of-view, as an apposed roll without knowing the target number (i.e. the defense roll has not been made at the time of the attack). I would use the same way of thinking in case the player would roll against a fixed, but unknown, target number. Once the player have made the roll and I reveal the target number, the player would not be allowed to suddenly invoke an aspect after realizing that he failed the roll  and re-rolling or add +2 to the result.

Please also note that once you have invoked an aspect to add +2, you are not allowed to re-roll, as the rules say that “Add two (+2) to the final die roll (after any rerolls have been done)”.

In regards to "always on":

Always on items do exist, the question is how much are they allowed to effect the story? The Dresden Files RPG focuses on story mechanics, not physical ones. Fate points and stunts largely represent controlling how much someone can interact with the story.

Lets use Dresdens duster for an example. It is always enchanted with defensive spells, this doesn't change. However, it doesn't come up in the story every time he is attacked. It comes up, say, 3-4 times per story. It is still there, still enchanted, possibly helping in a fluffy way (man, if I hadn't had my duster on that fight might have been much worse), but only effects the story 3-4 times.

Now we look at that same item from an in game perspective. It has 3 uses, so it can come up in the story 3 times. The player can then exercise their story control (fate points) to allow it to be used more times. It is still magic, still working, but has no mechanical, story benefit beyond 3 times.

So your players can have magical protective auras, supurlatively sharp swords, and glasses that pierce illusions, and those things may be always active. However, their uses and fate points effect how many times they may effect the story per session.