Your A50 1.7 is good, stop using it wide open unless you want a super narrow depth of field for artistic purposes. Make sure you see the little green focus confirmation light when focusing. Get a lens hood for it, all the fast 50's seem to benefit from them especially on the wider aperture end.
The rest are less than desirable lenses in my opinion.
Your choices for replacement lenses in your first post sound like better ideas than some of the ancient or variable aperture stuff that was being considered.
It is better to save up and buy a very few good lenses than have a laundry list of "good for the price" lenses.
If you really need a cheap but decent lens for now I found this one for under $100 with a hood to be quite useable:
SMC Pentax-FA 28-70mm F4 AL Reviews - FA Zoom Lenses - Pentax Lens Reviews & Lens Database
You can combine that with one of the crappy 70 or 80 to 300ish lenses for a good pair to carry around.
The K20D has poor high ISO compared to even the original K5, but you should have been using at least ISO 400 for the shots you took since you were shooting everything with wide open aperture which destroys image quality on those cheap zooms. I think parts of the bushes were also out of focus due to narrow depth of field but I can't tell at that zoom level.
The K20D underexposes everything, you have to boost the brightness in post processing or everything will always be too dark which kills the colors. This was done to help prevent blown highlights so I would leave it that way rather than bump the exposure compensation in camera to fix it like some do, but you should be aware of it when you take the picture.
Download paint.net for free if you don't have any decent software. Its no photoshop but its free and does most everything really critical.
Though most of my best pics were actually taken with my K20D (I did more shooting back then) the best upgrade I ever did was to replace it with a used K5 for under $400. Worlds better in a ton of ways but mainly freedom to use higher ISO without quality penalties. I would probably go with a K5II (or K5IIs) if I were to do it now though unless money was the primary factor.