Like you mentioned, the way everyone does FC is the best way to them.
Bottom line, you can do what you want. I set to serving pressure and leave it. As I mentioned, I have more room than taps. I have 6 kegs but can only have 4 in the keggerator. So for me it isn't a big deal hook it up to gas at serving pressure, purge and let it sit. After a week it isn't bad. At two weeks it is perfect. It isn't possible to screw it up this way but it takes longer. Because of my use of the beer and equipment this works best for me.
Another way is to purge, boost to 30PSI or so, rock it, let it sit then bleed and go to serving pressure. This will save some time off the wait. You will be drinking in a few days rather than a week. Here are the risks. Over carbonation is possible. Boost the pressure then you get busy with life and forget about it. Oops. Over carbed isn't the end of the world. If you go to serving pressure the excess gas will work out of solution in time. Be careful though you don't want beer going back the gas line into the regulator. It will screw it up and I have read where this has happened to people. Better option might be to leave the gas line disconnected, vent the pressure from the keg, rock it and vent. This will work the CO2 out of solution just like how you can work it in.
As far as pressure. 12 is a good starting pressure. There isn't a cut and dry right answer. I typically am closer to 10 in my system but it depends on what type of beer I am serving. Different styles call for different pressures. I try and shoot in the middle somewhere as I have a variety on tap all the time. The next variable is keggerator temp. Variations in how cold you like your beer will impact the pressures you want. Then there is equipment. Shorter liquid lines don't like highly carbonated beer. You will get a glass of foam. You can tune your taps so you have different styles served on different lengths of line to get a balance. I had a beer I took to a party a couple months ago. My portable cobra tap had a 3' line on it. I was getting too much foam. So I swapped it out with a 10' line and it was perfect. Don't want 10' of line taking up room in your keggerator, use shorter lines. I think the lines in my keggerator are about 4' long. To keep from getting too much foam though, I had to dial my pressure back to about 10PSI.
From what I have read, storing the tank in the fridge will cut it's life a bit. Not sure how much but a little. Like I said, the high pressure gauge doesn't tell you all that much. Some have a range that say replace tank or something along those lines. I don't know how they calibrate this. I suspect it is going to be at room temp not in the 35-45 range that most fridges are at. Also even at room temp, how long you can go while it is in the "replace" range will depend on how you are using it, how many kegs are hooked up. Are those kegs empty or full, how big the CO2 tank is (5#, 10#, ect), are you in the middle of FC a new keg, are you purging bottles while you use a beer gun? I just glance at it and make sure it doesn't say 0 PSI. I also have two CO2 (10# steel & 20# Aluminum) tanks so I always have plenty of gas on hand.
