Have Toyota Questions? Ask a Mechanic for Answers ASAP
Under normal circumstances where people don't change their brake fluid regular I would say you probably should change the seals or remanufactured calipers. But because of your service history and having the brake fluid changed you should be fine with the calipers that you have. If the pistons push down nice and smooth with no resistance or sticking issues and the dust boots have no tears or holes in them let it go you'll be fine for the next 50,000 miles.
I would not change them if you are only looking at another 50. If the flush was only don 30k miles ago you will be fine. It is only 9 years old and the rubber seals would be fine. If you choose to change them still home air pressure will pop them out or you can pump the pedal to push them out most of the way. If you do that you run the risk of pushing the master cylinder seals further then they have been and can cause issues. Pedal bleeding by pumping can also cause issue with the seals in the master cylinder so you should vacuum or pressure bleed if you do this.
No the vacuum bleeder will pull the fluid through the system fine no need for any tester or active testing.
If rust and corrosion is not an issue where you live then the rotors normally can be machined one time there's 1 mm to take off. Otherwise you can buy aftermarket rotors for the rear on this for probably about $30 apiece. I would probably recommend replacing them.