Apple Watch Series 7 (45mm Stainless Steel with GPS & Cellular) has broken - what are my options?

Back Crack & Power Failure

I got an Apple Watch Series 7 (45mm Stainless Steel with GPS & Cellular) in March 2022. Great piece of kit, especially for the exercise and activity capabilities. Made the mistake of not getting Apple Care+.

Unfortunately, I dropped it at an airport a few months ago following the usual post-security struggle to re-pack and re-dress. Cracked all across the glass bottom of the watch but still seemed fully functional. I took it into the local Apple Store and was told pretty directly that I'd be better off buying a new one, as the repair cost would be in the region of AUD $900. The watch was around AUD $1200 when I bought it, so this was probably true.

I decided to continue using it, but have been very careful to avoid any water-based activity since the damage was done. On Saturday, I was playing tennis with the Watch tracking my activity when it started to go haywire. An alarm went off, which turned out to be the countdown to calling the emergency services. Fortunately, it hadn't detected an irregular heart activity, which was my initial thought. The watch had become unresponsive, restarting the countdown to SOS every time I touched the digital crown or the side button.

At the end of the game, it was still messing around so I turned it off. Turned it back on and it was doing the same thing. The touchscreen wasn't registering anything and the only functionality it now had was the SOS countdown. In the end, I decided to leave it for a while and allow the battery to run down, hopeful that a fresh charge following an organic reset would snap it out of its malfunctioning.

When I came to look at the watch later, it was showing the charging snake (which I've read elsewhere is considered the Snake of Death). I put it on charge. A little while later, I tried to turn it on and the white start-up Apple was showing, only for the Watch to then switch off with a black screen. This happened half-a-dozen times and then stopped turning on at all.

I've tried charging it subsequently but no response. I think it's completely dead.

Comments & Questions

My assumption is that sweat during exercise got into the watch through the cracks on the back and caused it to break. I'd be very reluctant to buy a top-of-the-range model in the future, given that the stainless steel appears to be as susceptible to damage as the aluminium. It's a shame because I've always had pretty solid luck with Apple products and their durability.

1. What's the expected lifespan of an Apple Watch? The two-year period that mine has lasted feels like short change.
2. If I send the watch in for repair, I've been told that they'll likely replace the whole thing due to the damage and the power failure. Will this restart the Apple Care/warranty period?
3. I've got a handful of 45mm straps - would these fit a 44mm watch if I were to seek a replacement?