I have iMac 27, late 2013, with 28GB ram, 2GB graphics and 3,5Ghz i5. I have no complains. Premiere works fluently. After Effects works good, but if I have more advanced comps (Element 3D, a lot of layers) waiting for rendering could be a bit anoying. If it comes to DaVinci Resolve 12: editing is really anoying for me (compering to Pr CC) but color correction and grading isn't (when I work with for example viedos from BMPCC or C100 mkII). But You must turn on smart cache, and, when You have bigger project, is good to have half res playback.
I have NTG2 and I record audio on computer via USB Mixer (mixer must be plugged in) and I have a way better sound better than on, for example, Tascam DR40 (I tested it).