Helmut,
Don't sweat the rebuilt alternator issue. Price is high, but that's their markup. Rebuilt alts. are VERY common and plenty reliable if rebuilt by a reputable, experienced rebuilder. Example: PepBoyZ will sell you a rebuilt alt. for your with a lifetime warranty! Before anybody flames me, i'm not saying PepBoyZ is reputable. It's their supplier that is likely to be a big company like Beck-Arnley or someone like that.
I'd certainly drain the oil a bit. When it's too high, the excess oil gets blown into the engine thru the oil tank breather hose. Makes some oil smoke and pools oil in your intake manifold. If you're out this way, stop by and we can take care of it. I'd hate for you to have to take your car back there. But, it's probably good to take it back just to make them do some work that they will get paid NOTHING for doing.
I'd put some D-Con poison traps (unless you have pets) in the garage just in case. The master cylinder is inside the trunk! How'd they get in there? Did they say the nest is on the engine? That's probably where they saw it when they removed the alt.
Souk,
It's Optima. Ultima is the Kyosho RC car that you raced as a kid (or might still race- they're cool!)
I think a 911 can be a daily driver. It's just that the car is getting older and things are bound to fail. Gotta maintain it a little more than a newer car. My 92 Laser is a rickety pile that needs attention every so often to keep it going strong. I feel more confident in the 911 because it's more basic than the Laser.