i had some spare time and finally got around to re-registering on this site and saw your thread here. i will offer you some insight.
the direct drum is what drives your transmission in both 3rd gear and reverse. all automatic transmissions to get gear reduction drive one part of a planetary and hold another part. third gear locks the direct drum to the drive....or forward drum.....causing 1:1 and basically spins the guts of the tranny as a unit. therefore the rear servo has nothing to do with the third gear failure.
the rear servo under the cover is used to actuate the rear band. it not only holds the gearset in reverse but also applies for engine braking in the low 1 position. so if you pull it down to low 1 from drive range and try to kiss the steering wheel......your rear servo and rear band is working.
since you have two problems that use the same driving source, that is more than likely the culperate. starting the car in gear will not damage a direct drum. we do it all the time for my friends who demo derby.
since you have 1-2, it isn't a gearset problem or a forward clutch problem. you simply are not apply'n the direct clutch. if it is a new build it is possible that the steels are jamming the pack preventing apply. if it came out of a truck....especially a snow plow truck......they are prone to bending the stamp steel piston and blowing the clutch pack out the end of it shattering the direct drum backing plate.
here is a link for a great parts referrence to understand more what i am talking about. they also have good prices and products.
the 2-3 shift valve could be hung up as well, but i don't see that very often. also the center support can be damaged causing problems, but if 2nd gear is still there i would doubt it. an improperly installed shift kit will also do the same things you describe.