As for the wide to short-telephoto range, the anterior question is whether you need primes or a good zoom (e.g. Tamron 17-50 or the Sigma 17-70 C mentioned above). This is a common discussion in relation to pet photography:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/195277-reco...portraits.html
You will see in that thread that some people suggest a Tamron 28-75mm f2.8. Fast and sharp enough. Would nicely complement your 10-24 and 55-300.
However I take it from what you have said that you are already leaning towards primes, and particularly the plastic fantastics (DA 35 and DA 50). You can't go wrong with these lenses. There is a whole thread of photos taken with them so you can see for yourself.
Some people will argue for other prime lenses in the normal to short-tele range, like the three amigos (FA 31, 43 or 77), the 40 ltd, 35 or 50 macro, DA*55 or 70. Most of these are more expensive, but if you are using a lens for pro photography could be worth the investment.