Damn!!!....um, I mean, DIM headlights

[Cam1970]

Hey all, posting this question regarding my wife's car (really, cheack out my own....). She has a '70 240Z, pretty close to stock, with remanufactured carbs, new distributor, a/c, etc. We recently had to have the gas tank flushed, cleaned and three small pinholes soldered, so she's still hesitant to use this car for her daily commute, which is 70 miles each way.

Three questions: the carbs were adjusted at the mechanic's, who told us to come back in a week after some driving to re-adjust them, taking into account the heat here in TX as well as the use of the a/c. I'd do it myself, but the tach doesn't work, and we need to know the rpm in order to synchronize them. Question is, barring having to take apart the dash (did that once, she stated that it was a perfectly valid excuse for a divorce), is there at least a part that we can use to determine the rpm?

Second, the a/c works fine, making The Wife very happy, but there's a puddle of water under the dash on teh passenger's side everytime she drives, with water condensating on the evaporator. Not being a refrigerant guy, or even remotely used to Datsun parts and mechanicals, is there something that I can do to prevent the water from evaporating inside the car?

Third, she replaced both headlights when the drivers side light finally, after 34 years, blinked out. Now the very same light is running dim; please please tell me that a simple dying fuse can do that, as neither she nor me are electric experts.

The Wife really loves this car, and has no qualms of working on it on her own (she knows her way around a toolbox, no rude puns intended), but still lacking a factory service manual, doesn't want to start digging around under the dash. Any help, advice, greatly appreciated by me, who in spite of driving around in a veritable tank, still thinks these Zs are cool.