Not sure I exactly understand the question…the season is as long as the season is. This is usually determined by your sport and the competitions you enter. For example, football season is something like 10 - 16 weeks plus playoffs. Track season will vary depending on which meets you enter (indoor is shorter than outdoor) and will usually culminate in some kind of championships. The in-season is the time between the championships and the first meet you enter for that season.
How many mesocycles should be included in a single season?
A sprinter will use either double or triple periodization over the course of a year. In each of these periods, there will be a training phase, a competition phase and a recovery phase. See page 101 of CFTS for a nice diagram. Note however that these phases will generally blend smoothly from one to the next, so it is not an abrupt transition.
Within each season what is the objective and how should they be ordered?
Speed, Speed Endurance, Strength, MaxV, Acceleration, Hypertrophy, etc…
Depends on the athlete, but generally, it doesn’t make sense to me to develop speed endurance before you have the necessary speed (MxV)in place. Likewise, it seems that you will need to develop acceleration to get to that speed. (gee, this sounds like a short to long philosophy!)
Hypertrophy and general conditionong should be addressed during GPP (early in the training cycle.)
Is active rest the best option for this?
Best option for what?
Should younger sprinters (not running sub 11 yet, or less than 3 years of training experience) try to peak or just simply keep training through all meets???
Younger sprinters will need longer GPP and will likely look at double instead of triple periodization. I certainly wouldn’t try to peak too often with a young sprinter, but I think it is important to work to make sure they come into important meets fresh and ready to run fast. Also, deloading is an important component of speed development. That is, when the other CNS stresses are reduced, at sprinter has the greatest ability to hit top speeds which then enables them to build off of those speeds in the future. Finally, it is probably good to get some experience with how an athlete handles a training taper and what works and doesn’t work for that particular athlete as a basis for future plans.
Note that I would never want a sprinter running a meet if they were not ready to perform well. They should be completely recovered from their last session. Also note that peaking for a younger sprinter is probably less involved since they will likely have a shorter taper based on lower CNS stress and less ability to keep their stimulus for a long period of time.