2 questions to anyone who might be able to point me in the right direction:

1) Bought my 2000 ES300 Platinum Ed. from a Lexus dealership (not certified pre-owned) in '05 with 69K on it and no incidences in it's lifetime. She's at 140K now, and as I've never done anything with the tranny fluid (don't know if anything happened during oil services) I need to get on it. I've read many contradicting posts as to how to properly go about it, though, so I'm looking for some advise. Drop the pan and clean the screen...; flush; mechanical fluid exchange? Can this be a reasonable do-it-yourself or should I make the investment and leave it to a pro?

2) 6 months ago I pressure-washed my engine, and thereafter my check engine, transmission, and VSC and VSC-OFF lights have been on. Stranger, and these symptoms exist only when the headlights are on, the light indicating that the car's in reverse will always be on as well as the light whatever gear I'm in, when shifting into park the car jumps fairly violently, and simultaneously all rear lights are out minus the two outermost and the central back-glass brake light. I pulled all corresponding fuses, but none of them are blown. What the hell could be going on here?

 

Update:

As for my warning light/electrical issues, I looked at the taillight wiring in my trunk and uncovered that one of the wires (white sheath with black line) was split at the hinge elbow, probably from overfilling the boot and pinching it when closing the lid. After reconnecting it all my taillights work properly, my car goes from park to reverse without jumping, and my gear indicator lights are functioning correctly on the display and all the warning lights are off. Hopefully that's it, but to anyone out there who knows about these things should I still be concerned about the warning lights on the display? If not, I figure I just saved about $300 or so in repairs!!

 

For the price of a new filter, toss the filter and replace it..They are like $25. On the engine washer (bad), you are on your own.