Lexus cars are good but the V8 Lexus LS tends to be expensive to maintain and repairs. I would look for a 90's ES rather than an LS.

Not really, just because it is a really old car (taking about 23 years old car) and if also the mileage is low, all the plastic/rubber parts need to be replaced soon. The repair cost of those V8 engines are astronomical and that's why you will find those cars depreciate so fast despite being a Lexus product.

It depends on what you mean by "good". I've had mine for 22 years and hope never to part with it. HOWEVER, I know exactly what I have. A great deal depends on the particular car you may be considering buying and how it was driven and cared for.  I've had only 2 leaks: Valve cover gaskets, of course, and a cam phaser. Those are expensive to fix. VVTi solenoids can fail but replacements are cheap and easy DIY. Timing belts have to be done at 90K or so. Nothing else I can think of. Never buy without a GOOD PPI from an expert. Change oil yourself. Don't trust amateurs for anything. AVOID dealers for any service. 

Bad battery cells can produce all sorts of wild gremlins. If something weird happens, load test the battery FIRST.