Do you mean the 35mm f/2.4 or f/2.0?

I can't imagine that the 31mm isn't significantly better than either of those 35mm lenses, possibly in sharpness and contrast and certainly in rendering. As for the 43mm, it's the only FA Limited I have and it's a very different animal from my A 50mm f/2.8. The focal lengths are similar and they're both great but the 43mm renders much nicer and isn't good for close focus, while the 50/2.8 is very, very sharp but rendering is very different, not as smooth.

I've used it on film and it seems fine.

I really like the second image, it allows me to imagine I'm there.

For something cheap & cheerful but quite capable the DA 50mm f/1.8 is your best bet if you want to get started ASAP. Not the focal range you're looking for but will be faster than any zoom and will allow you to at least start using the camera with a general-purpose prime.

I would suggest that photos of the equipment would help a lot to sell them.

Perhaps there are local charity organisations that look for donations of photographic material?

A nice set. I too was in Venice in 2018, in January. As we were lucky with the weather it was the ideal time to go - not too many people, especially in Venice, which is well known for the huge numbers of tourists it attracts.

I'd agree with others that the adapter is perhaps a little warped. I've never seen that with a genuine Pentax one but maybe it's a fake, though I don't believe there are many fakes out there, just cheaper designs made with cheaper materials.

I think the manual states that the adapter should go on the lens first, then onto the camera but I always put it on the camera and screw the lens in and have never had a problem with it. The only problem I ever had with an M42 adapter was a third party one that got stuck while trying it out in a used camera shop. Luckily they also do repairs and quickly removed it for me, but the experience put me off M43 lenses on my DSLR for years.

I have a liking for waterdrop-on-plant photos though they can be very hard to do - small item to focus on, potentially moving, and blown highlights due to any light source appearing in the drop(s).

SRS Microsystems has been selling K1000s with an M 50mm f/2 lens for £250, but I'm not sure in what condition. That's a crazy price in my opinion, for the most basic K body and the most basic M lens, even in mint condition. I'd say £60 tops, but if SRS are good at finding idiots who'll pay silly money then good for them.