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You got a great deal on the glock. The ruger was a fair price.
As far as shipping back to glock, I don’t know. I doubt they would eat shipping costs though. Which means for that price, I would find someone who knows glocks and have them go through it and replace any parts that need fixin. I would look at a few aftermarket parts as well from vickers tactical.
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Great deal on the Glock. How does it shoot?
Many people have taken the Glock armorer’s class. I’m a civilian and enjoyed the class. I recommend finding an armorer. They could detail strip, inspect and test the G19, replacing worn or damaged parts as necessary. Replacement Glock parts are very well priced.
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I think you got a good deal on the Glock. Parts are cheap and they’re relatively easy to work on, so you can change the springs and swap the backplate without too much cost or effort. The sight issue is easily fixed as well. Dude probably turned it around so he didn’t have to look at the white outline. In truth, the plastic factory sights are pretty much just good for filling the slots until you can get some proper steel sights. 
Glock pistols use trigger housings with caliber specific ejectors. This is why the 19’s ejector looks different that that of your G22. It’s fine…Don’t worry about it. The rest of the wear sounds pretty normal too, IMHO.
As for local armorer vs a trip to Glock, I’d say it’d depend on which is cheapest. Local guy will charge you for parts and labor, where with Glock you have to pay shipping, which could be $50 to $70 by the time it’s all said and done.
If it were mine, I’d probably just send it to Glock rather than calling and driving around trying to find a local armorer.