Ok.....don't fill the jars all the way to the top. This will cause boil over for sure.....which will not only result in wort loss......but the problem you've already discovered....sticky jar syndrome. This causes a problem down the road when trying to get the rings off your jars (becasue you just glued em to the jar). I've had this happen to me. Plus it's not very sanitary if you ask me. Provides something for bacteria and wild yeast to adhere to which makes it more likely that these things can find their way into your starter.
I fill my jars to right at or just below the threaded part of the jar. This seems to work out pretty good. Even doing this though, sometimes the jars get a bit sticky. I like to take my rings off after cooling and sealing of course and wipe down the jars with a wet rag. I just leave the rings off after this most of the time becasue thier only purpose is the hold the lid down until it seals anyway....although they do protect the lid I guess from getting bumped around and losing seal. Shouldn't be a problem though.
Also, FYI, I like to wipe down my jar lids/rims everything near the top of the jar with a papertowel saturated with alcohol before popping the top and pouring into the starter. Just a good sanitation practice if you ask me.
As for shelf life.......pressure canned, sterile media should be good for many years to come (although mine always gets used within a year). I store mine in the basement and try and keep them protected from light to try and avoid staling reactions like would happen in the beer itself. That said, the starter wort should not go bad for quite some time.
Another pointer though....since we're on the topic of canning. I like to pressure up jars of sterile water as well. This way you can pour off/siphon all of the nasty tasting starter beer and use sterile water to make your yeast slurry before pitching
Let me know if you have anymore questions.