I'm not really sure it isn't stretched. It just looks OK and doesn't seem to have any more slack than when new, although logically it probably has a bit.
You need to measure it either with a plain old ruler or a guage. Eye-balling isn't going to work for the majority of people.
I've only had the bike a year! In more than five years regularly riding my Trek mountain bike on and off the very gritty, dusty, muddy and potholed roads of this part of SE Asia I've had to change the chain twice and the cassette and crank once.
Those 2 chains must've lasted so long because you cleaned and oiled 'em between every ride, right?! ;-)
Isn't 'front chainrings' the same as the crank?
Um, nope. The pedals attach to the cranks, and the chainrings typically attach to a spider on the crank, although on my bike, it's attached to the bottom bracket spindle.
Also, FYI, chainrings are implicitly on the front, although they're still technically sprockets, as the rears are.
Don't know about Sram chains,
Don't get hung up on SRAM, Wipperman, etc. It's all religion, i.e., subjective. Do your own research, which is fun itself. :-) But just be sure that you what size YOU need. There's a variety of sizes out there.
... having a chain tool plus master link sounds a reasonable compromise.
On my X-Canada tour, I took a chain gauge, chain tool, spare chain and links/master to handle my driveline needs. I took the entire spare chain 'cos I didn't want to shop for that specific chain (not a common one) or mail it to myself (what would happen if I arrive at the PO on a long weekend when the PO is closed? Then I'm 'stuck in that town for a couple of days). It was a lot easier to bring the spare chain with me.
I don't know if you've ever heard of Sheldon Brown (now deceased) but he has a LOT of the answers you're looking for at www.sheldonbrown.com
His web site may not have ALL the answers [to cycling] on this planet but it has a ton of info all in on place. Once you start browsing his site you'll be up all night reading it! RIP Sheldon.