If you have color slides developed, it doesn't really matter who develops it - unless the Contax you're talking about is 35mm, anyone doing MF and LF slides these days will be doing a good enough job. I've no experience with color transparencies or B&W film, but especially B&W developing is a very different beast and does require expertise. You can start doing it yourself with very modest investment, which might or might not be interesting for you. I couldn't be arsed.
FWIW my workflow with MF (and recently LF) slide film: shoot, have it developed by local shop (who sends it to god knows where), scan proofs and for-web shots myself with Epson V700, have keepers going for large prints scanned by a pro drum scanning service.
Also, color transparencies have less
dynamic range than any modern dSLR. Again, don't know about negatives, I think B&W might be on par with a good dSLR.
As others have pointed out, digital and film cameras are very different beasts. You have to really
like film and the process to be bothered with it, the considerable time and expense in buying, developing and scanning it. I'm always careful with the qualitative assessment of digital vs film, but nothing beats a well-scanned MF or larger Velvia or Provia
But film is not good for many subjects - or more accurately, digital is better-suited for many applications. Film is much more restrictive, but many revel and embrace that.
I have the Oly E-PL1, and you can't really go wrong with MFT. There are new lenses being released soon, a few being announced, and new manufacturers have joined the MFT camp. Sony's NEX is also promising at the same form factor, although its UI is reportedly very clunky, and I believe lens choices are more limited.
To close off the ramblings, for film I'd also consider an MF rangefinder folder, Mamiya C220/C330, or Rolleiflex.