K-50 as an entry-level DSLR

Hello all,

I'm new to this neck of the woods.  I'm primarily a mirrorless user, but I'm in charge of a group of photographers and videographers that cover comic conventions.  Myself and another generate most of the visual content (On my E-M10 II, E-M10 I, and Panasonic G7), but now others in our group are getting interested in actually taking pictures (primarily for use in our business, although also as a hobby.  I sent one an old Oly Pen to play with the in the mean time, but there's another looking to buy his own kit.

In particular, he is absolutely set on a Pentax K-50, and I just wanted to know if it was the right camera for the job.

We take pictures in all sorts of lighting conditions: dimly lit or outside in the sunlight or at night on the street.  We do full body and half body portraits, occasionally group pictures, and sometimes headshots.

In this particular case, photography is the main focus of the body, with video taking a distant second in terms of importance.

Since APS-C has a different 35mm equivalent, and since the image sensor a bit larger, I'm unsure of the aperture specs and focal lengths to look for in primes or zoom lenses, or which third party manufacturers make solid lenses for the Pentax.  I know Sigma and Tamron make them, but I'm unsure if any in particular (outside the globally praised 18-35) are worth moving outside the Pentax lens offerings for.

Any and all thoughts would be appreciated.