Best Program to Compliment Crossfit?

Hello.  I've been pursuing the foundation series for a few months.  Since I have started, I have refined my goals and wanted suggestions on which series to follow and how to work it into my current routine.

Goal #1 - Injury Prevention.  I have serious overuse injuries to my adductors from a decade of marathon training.  I am doing the middle splits stretch course once a week.  Should I increase or stay at once a week?  Any other suggestion to guard against injury?

Goal #2 - Achieve advanced crossfit movements.  I still do not have muscle ups.  I would like to master these movements.

Goal #3 - Solidify handstands and pistols.  I can do a handstand walk, but it's not pretty.  Same with pistols.  Looking to sharpen these skills.

Finally, how should I pepper these courses into my routine.  Right now, I do crossfit programming Mon, Tue, Wed & Fri.  Thurs, I do skill work, usually snatches.  Sat is a medium run, about 7 miles.  Sun has become my middle split stretch day.

How much GST can I pepper in without over-training?  I am a masters athlete and not getting any younger.

Thanks for any advice.  I find these courses valuable, I just need to dial in the details.

PS - Is there anyone in the Bay Area who knows the courses well enough to judge my mastery?  I was thinking of seeing a coach once a month to make sure I am on track. 

Goal1 : nope, once a week it is fine. injuries must be followed by rest and then tissue reconstruction with adequate exercises for the legs. foundations 1 is perfect for your legs rehab.

Goal2: for muscle up you need to build up basic strength, tissue and AFTER advanced rings strength (also if I do not consider a muscle up an adv movement). begin with foundations. it will save you from bad elbows problems.

Goal3: foundations 1 for the legs and handstand 1 for your HS development and shoulders injury prevention.

You need to set your primarily goal, if for you it is build up a body capable of holding certain elements then you should give priority to GST.

Honestly a good yoga class would take you further to your goals than Crossfit 4x per week.  Per Goal #1, your legs (calves, quads, adductors, abductors, hip flexors) are likely very tight.  Going after one problem area and doing a middle split stretch series is okay but you need to follow a complete hip/leg series that addresses mobility & strength if you are serious about injury prevention.  Stretch more, daily during your warm-up and cool-down is recommended, more on days that you focus on mobility.  Per Goal #2, I have no idea what "Advanced Crossfit movements" are but a strict muscle-up I hope is not considered one of them. Per Goal #3, dump handstand walks they will do very little to help you develop a clean handstand because you probably are expending a lot of effort and zero time with your body in the correct position so get to a wall and do those common wall handstand drills.  Finally, if you can afford it see a coach daily, not once per month.