I'll try to make this as quick but informative as possible..
Whole Coast Guard is broken into two Areas: LANT and PAC. There are numbered Districts in each Area. HITRON is in District 7, I work New Orleans in District 8. Each District has Sectors. HITRON is is Sector Jacksonville. Sector New Orleans works the local area here.
Each Coast Guard Air Station has a CO, XO, OPS, EO with their respective departments. That Air Station CO works for the District Commander. AIRSTA CO usually an O5 or O6...District Commanders are 1 Stars in most places.
For inshore or near shore work (SAR, Maritime Pollution Response, PWCS/Homeland Security Patrols)...The District authorizes the Sectors to request/direct air coverage. For the helos deployed to shops or to our "other operating areas" the helos gets TACON/OPCON shifted to Area and sked outta there.
That's the broad strokes...There are some special cases like anywhere....but that covers the major stuff.
As far as Aviator careers- I'm still pretty young- but the story goes:
First Tour= 4 years. Make AC, Make LT, Work on a Masters, Get your first 2-3K hours.
Second Tour= 3 years. Work on a specialty...Finish a masters, Get into OPS, Safety, Eng, Admin. Also expect this to be an OCONUS tour...HI, AK, or PR.
After that- Do a "shore" tour in your secondary specialty. I'm planning on getting a Masters in Human Performance Technology...so I'll be a training officer somewhere. Then go back to a department head/senior watch pilot job. And flip flop accordingly from there. Some folks do it different...but again- There are always exceptions to the rule.