You really need to start by at least figuring out what sort of focal lengths you are interested in, what kind of budget you might have, etc.
But I can clarify a couple of things:
- there are no "Limited" manual lenses; these are all newer AF lenses
- M and A lenses (and FA and DA, including the "limited" series) *are* bayonet (aka K mount)
- takumars *are* screwmount (except the takumars that are specifically listed as bayonet or k-mount)
- "A" always beats "M" in terms of usability, since you at least get auto-exposure and a full-time meter reading, plsu full flash functionality. But they are also pretyt much always more expensive
- zooms or primes is a totally different question in general. But to the extent it has any relevance here, "most" older zooms are not as good as modern equivalents, whereas "most" older primes are.
The standard suggestion is to find some of the M or A series (or the older k-mount series lenses that were neither "M" nor "A" - just labeled Pentax, not Pentax-M or Pentax-A) primes in the particular focal lengths that interest you. The ones that are easily found and cheap (at least for the "M" versions) are 28mm, 35mm, 50mm, 100mm, 135mm, and 200mm. A few older zooms *are* considered good, such as the M35-105/3.5 and A70-210/4 (I think).
See:
Stan's Pentax Photography
for lots of opinions on these. Mostly from the film days, so take the specific discussion of focal lengths with a grain of "crop factor" salt.