since I was 10 and all the way until 22, I shot in film only, fortunately I had a "digital" body with Auto focus and a very steamlined pentax mount system (this was 15 years ago when I first got my very first Pentax "digital" film camera and 17 years ago when I got my first Olympus OM10 with 50mm prime) I went into DSLR kicking and screaming and not really happy with the FOUR THIRDS system in the DSLR sized offering - BUT now the MICRO FOUR THIRDS system is imo excellent, the same sensor but with the right kind of body and lens types, and I think going pana or oly in the micro will be the best choice imo, as the sensors havent changed but the processing, speed and the lenses have been fine tuned to support this interesting sensor type.
a. Will either the Panasonic or the NEX let me get some more years out of my lenses?
EDIT: Read Maestro's answer
b. What adapter is required/recommended to make that marriage happen?
EDIT: Read Maestro's answer
I am assuming the lenses listed were and are used for a Film Pentax body at the time, but you manage to use them on your Canon A-1 - is that right. Assuming I read your post correctly....
To answeer your B question for your TAMRON lens - "This lens needs a PK (M) adapter. It can turn into a Pentax-A lens with a PK/A Adaptall mount."
So that mean YES, your lenses can protentially be used for digital - but at the moment, only for Pentax bodies. (Caveat: Im sure there are other mounts for Canon DSLR and Nikon DSLR and others but most of the literature point to pentax and since the OP was talking pentax, I am only making an assumption)
c. Specifically with regards to using my new camera's movie capabilities, where zooming will be critical, which of the two systems [or some other] would likely give the best results with manual focusing. I know I don't want my movie's sound to be ruined by the noise of any part of the apparatus.
Movie recording needs Image stabilisation or some kind of shake reduction - And zooming only aplifies this sense of camera shake. Unlike deicated camcorders which uses a motor to zoom and uses anti-shake, point and shoot cameras dont have a motor - we use our hands to twist the lens - Im afriad the best way is to get a hold of a camera with a long lens and try out the vide yourself and see what zooming is like WITH and WITHOUT some kind of shake reduction.
d. What current lens or lenses would you recommend to go with whatever new body is chosen?
Kit Lenses on the Mirrorless camera offerings are actually really decent. They normally come in twin kits, offering a prime and a zoom lens. If you are going into DLSR, and you buy a pentax camera, a mount is all you really need a lot of time reading on how the relationship with 35mm lenses work with DSLR cameras (especially cropped frame bodies)
Normally, if you go for a mirrorless camera body, Id get a twin lens kit that has a prime as currently all the brands are making pretty decent primes - the zoom, well that depends on how flexible you want the camera to be and how big and bulky you want it to be too.
Hope this helps
Anyone please correct me on my information if there seems to be something wrong, I normally sit and do my research but Im tired and I did only a little bit.
1) Olympus OM1 [Zuiko Auto-S 50mm f/1.8]
2) Pentax MZ-60 [Sigma 28-90 & 100-300]
3) Canon 7D [EF-S 15-85 & 70-200mm f/4 IS & 50mm f1.4]Leo's Flickr Page