I did a quick check of a few of the usual sources, and came up empty. Astra was closed after the owner was killed by Basque Separatists in 1977, so a used barrel is your only likely route. They DO show up on auctionarms and gunbroker from time to time.
Not possible to determine. No records, Astra is out of business.
100-400 or so
100-300 usd or so
The model number should be stamped on the barrel just above the trigger guard.
no
No. The 9mm is not compatible with the .40 caliber frame/slide. On the other hand, you can put a .357 SIG barrel into a Glock 22 and use your .40 magazines.
You have a Smith and Wesson model 14 38 special. The 38 refers to the diameter of the barrel. That barrel is 38/100 of an inch in diameter. A 45 automatic has a barrel that is 45/100 of an inch in diameter. A 9mm has a barrel with a 9mm diameter. You can shoot 9mm ammunition from a 38 special. A 22 pistol has a small diameter barrel.
The safety is just to not load the chamber until you're ready to fire it.
No. Some .40/.357 Sig pistols can be converted to fire 9mm simply by dropping in a 9mm barrel and using the 9mm magazines, though. Not sure about the Glock.
Which one? They are several different models.
200-600 USD
A 9mm. You will have to provide a detailed description of all markings, type of action and finish for more help.