Newbie - Inverter Coolant Pump Leak

Had to make the trek to civilization yesterday, so swung by my old mechanic. He told me two things that I'm quite concerned about:

1) He tested the existing coolant in both the engine and inverter loops - said it was testing as way too much water (not 50/50). I've only ever put the pink Toyota SLLC in, as directed by the manual. The coolant in the system was pink when I got the car, so I had assumed it was the right stuff - however, now it sounds like maybe they had put in the red coolant, then topped off with a bunch of water? I'm also assuming this is very bad news - that can't be good for the system. He recommends completely flushing both systems (he would have done it for me, but doesn't have the right scan tool). He did say there was a bit of air in both coolant systems.

2) He shone a light into the coolant under the radiator cap and pointed out that it looked "sparkly", like there is stop-leak in it (I had had the local guy pressurize the radiator and check for leaks - he said no leaks, but if there was stop-leak in there obviously that isn't the case). He said if there IS stop-leak (and hence a leak), flushing the system might blow the leak open, therefore more repair work than I'm comfortable doing. I'm a little bit ticked about this - the previous owner swore no leaks, no issues at all (and he's the pastor of a local church!).

I'm thinking I should make the trek to the dealer and have all of this done at once (flushing both coolant systems, recharging AC, inverter pump hose leak, possible radiator leaks). Just the system flushes will probably be around $300; any idea how much I'm looking at if there is indeed a leak in the engine coolant system? And the dealer is two hours away - quite a ways to drive with bad coolant, if that watered-down coolant is going to have seriously adverse affects.

Again, thanks for all the advice.