The XPS oil is fine, that's what you want, full synthetic. May need drain the old oil, wouldn't hurt to replace injection lines while you're at it.
Pretty much all the 2 strokes run the 16 size battery, CL16, EXT16, YB16 etc. I'd buy an AGM battery, you won't need to worry about losing acid if you toss the ski around. I bought a flooded battery for the GSX last year and had to fill it several times after I figured it out it was losing acid. AGM this year. I bought a Deka EXT16L from amazon. Pay close attention to which end the positive and negative posts are, you can buy them flipped the wrong way.
Either Hydro Turf or Blacktip, put it in a search. I prefer the Hydro Turf mats, and you can get a decent discount using the code HYDRO15 if you go through the sponsored vendor
PWC Performance Parts Discounted - PWCMuscle.com. I used a diegrinder to get the mats off, cut them down flush, drill the rivet out and fill with an epoxy type product like Marine Tex. Clean the surface with acetone and buy the peel and stick option mats.
I've never seen gauges that look that bad, search ebay or call westsidepowersports. Should be easy to remove, unplug the old and plug in the new.
Judging from the rust, at least one of your skis needs new spark plugs. Last word of advice, I personally wouldn't even put them in the water and run them without going through the fuel system, rebuild the carbs with OEM kits, new fuel lines, new fuel selector, etc. And draining and refilling oil in the jet pump. The last thing you want is to have them run like shit and lean out, oil lines break, or fill up with water on your first trip. I understand you bought them seeing them run, but that's about it, it's a whole different challenge when it's underload in the water and bouncing all over the place.
