Alas its true. Everything requires some form of calibration, and yes, parasitic capacitances will vary, but those can be zeroed out for a short period of time. The reason I started the thread was to gather idea's about methods (well used, or new/exotic) where-by one can trade the need for a 'standard capacitor' for other, more available 'standards'. In my case, a high accuracy voltmeter, and some precision (0.1% 15ppm) resistors.
About ESR, one of the links I posted does a pretty good job of measuring ESR. Uncalibrated (built only using 10% caps, and zero'd) it claims to get 5% accuracy for L, C, and ESR. My build seems to be pretty much spot on regarding ESR, with ceramic SMT caps soldered to leads getting <2mohm. With 1206 100n having a lower ESR than the 0805's (which in theory should be right). Many SMT lowesr caps from laptop motherboards also seemed to agree with the datasheets more of less (ESR varies considerably).
As far s 'what micro to use', any really
AVR's are quick, and have plenty of beefy peripherals, PIC18's (even PIC16's) will do a similar job. I think for this application, it is much more a case of 'what ever you are acustomed to' as opposed to 'which one can handle things better'.
Apologies for leaving this thread for so long, a got a pretty good contract, its eaten up much of my time.
As a small side issue, I also started a thread about measuring absolute inductance (asking you clever folks all sorts of awkward questions!), along with saturation current - mainly for power magnetics. Which is really the inductance version of a cap/ESR meter. I have not forgotten about either of these projects, and hopefully when work calms down, can collate more information, and come up with a prototype of each or perhaps both in one unit. Lord knows theres enough DIY LCR meter's on the web, but an L meter specifically for SMPS inductors/transformers (L, Isat, DCr) isn't so popular, and I would definately find it handy for dirty custom wound magnetics, or salvaged parts.
I will try to be more active in the forums, I owe it to the many who have shared their knowledge/experiences.