I don't know off hand what starting thickness is for stock pads, but they still look OK to me. Once pad material is thinner than backing plate I'd start shopping and there are the squeal indicators as well. For track days they recommend 50%+ pad life remaining generally, but you kinda gotta gauge your skill level and typical pad wear at an event--I've went thru a basically new set of pads in a weekend. Different car, 500hp and 3000lbs, but it's still pretty tough on brakes. If you're not sure go ahead and buy some now and then you'll have them on hand when needed.
Some disturbing info posted at the end there. Not lubing the sliding pins, unsure of torque specs. For something like brakes this is something you need to go about the right away, especially if you're tracking the car. Torque spec is 20 ft-lbs from the manual i have
This is what you want for caliper lube: I put hardly any on the pads themselves... just a tiny super thin layer/smear on where the caliper/pistons touch the pad, and the pins themselves of course. Don't need a ton of the pins, just clean them all, and a nice thin even layer
Brake fluid, I have ran ATE type 200 on above mentioned car and had zero issues, but I also religiously bled/flushed brake fluid before events. It's a good value/performance compromise. I also recently found that JEGs started making/selling their own brake fluid and its an even better value. I bought a bunch but havent used it yet. I also like the smaller containers so I don't have to open and spoil a whole liter at once.
Another option is getting Castrol SRF, which has an incredibly high wet boiling point, so you really don't have to worry about flushing it. Maybe just a quick bleed before an event. I have seen several guys who use it on their dedicated track cars (that they drive a lot), and it was good for the whole season....probably longer, but they did an annual flush to be safe. Yes it's expensive, but depending on how many events a year you do/time you spend on flushing brakes..might be worth it.