Congrats, AlexVT!

I really like my 229RDAK. Not sure how familiar you are with Sigs but I can give you a few tidbits:

Great safety system that includes four basic safey features:

Decocker (pretty obvious), drops the hammer safely on a chambered round
Intercept notch - catches the hammer as it falls using the decocker. Holds the hammer away from the firing pin and acts as a drop-safe mechanism
Disconnector - lifts the trigger bar as the slide moves rearward to prevent firing out of battery
Firing pin block - prevents pin from moving forward unless trigger is pulled to rear.
ETA - Oh ya, forgot to mention the obligatory "remember, all mechanical parts can fail"

If this is your first Sig, I would highly recommend the Sig Armorer's manual done by Chris Orndorff. It's less than $25 and is a great resource for maintenance procedures and understanding the Sig Handguns. Top Gun Supply is also a great resource for resource. I'm not affiliated with either, just passing along my experience. You can find Topgun Supply here

I can't help much with the age, I can only tell that on the older West German models. Gotta go now, maybe someone else will chime in with more info.

From the Sig Sauer FAQ website:

If the gun was manufactured or imported by us, we can get the date of manufacture from our Records Department. This is offered as a service: SIG OFFICIAL DATE OF MANUFACTURE CERTIFICATE $49.95 To order, please call customer service @ (603) 418-8102 with a Visa, MasterCard or American Express. Please allow 2-3 weeks for research, printing and shipping.

No expert here, but I can help with the SRT. With the gun empty, dry fire it, and hold the trigger afterwards, then rack the slide manually while continuing to hold the trigger depressed. After racking the slide, slowly release the trigger and wait for the click.