Regarding stop-loss: back in WW2 allied bomber crews went home after 30 missions, and fighter crews after 25 missions. This was due to the high rate of casualties among these units. It's possible (probably?) that the Colonial military has a similar protocol.
Unlikely, considering they were fighting a defensive war against the Cylons as far as I understand it, and definitely were not in a strategically favourable position.
When the US and British air forces started conducting daytime bombing raids over continental Europe, they were on the offensive and the Luftwaffe was defensive. Luftwaffe, by their policy as well as lack of other options, kept their most experienced pilots on the front lines flying mission after mission after mission; that's one of the main reasons the German aces scored such high kill counts. The Japanese did the same. And, unless I'm much mistaken, the Soviet VVS also didn't really let pilots out of service after certain amount of sorties.
The US and British air forces used a system where airmen flew their allocated sorties, and could then return to home if they so wanted. On the other hand, the commissioned officers were usually rotated off the frontlines after certain amount of combat sorties, and re-assigned to training duties.
This is also one of the reasons why the pilot quality in USAAF, USN, USMC, RAF and Fleet Air Arm increased substantially as the war progressed. While the Germans and Japanese burned through their excellent pilots from the pre-war time, the training of new pilots for them suffered as the veterans did not get to impart their experience on the new pilots; while in the US/UK air forces they did.
I'm sure the Colonials would have done the same as US/UK air forces, if they had the chance to do it. But we don't have enough information about the Cylon War to determine whether they could have feasibly had so much freedom in recycling their frontline flight crews like this.