I do like the all but (to me) two have processing issues with regards to HDR. #9 overdoes the HDR unless you can cure the edge effect between the wall and the view where there is a halo round the arch and #6 suffers similarly but darkens the surround to the join instead. Sadly that's a common problem with some HDR programs and needs to be watched for. Editing each part of the image as a separate layer can sort that out. However the sunset in #8 is quite super.

You're right. I'm thinking of the older auto equivalent on the flash itself! The ME Super didn't have TTL through the camera lens but could use the auto feature of the flash'.

Just to add, the green button is for the camera metering with manual lenses; that won't work with flash so just set the lens aperture to what the flashgun requires and you should be fine. Adjust the initial image exposure to taste if necessary!

Are you aware of how to use flash guide numbers? A bit 'old school' I know! That is what you'll need to use though the flash gun may have a table showing f numbers for given distances to help.
'X' sets the flash sync speed, around 1/125" (to be precise it's 1/180" with a K-2ii) so use that.

I think that Metz's trigger voltage is not too high for a DSLR but it's something to consider with older guns.

You may well be able to use the flash's TTL setting - you set the f number based on the ISO used (it may say ASA which is a direct equivalent).

Basically just do what you did with your ME Super.

Don't thinks it's a macro lens (maybe close focus) but gets a reasonable write up at PF https://www.pentaxforums.com/userreviews/auto-super-paragon-pmc-28mm-f-2-8.html

Up for sale already, or just the brown paper wrapping?

Because there's an instruction in the exif to rotate it by 90 degrees, which PU has done.
I guess the camera moved a bit during the exposure? Why didn't you up the ISO to get a faster shutter speed and a sharper image then process the raw file to bring out the shadow detail?

The usual two lens kit comprises the 18-55mm and 50-200mm f/4 - 5.6.

Thinking about this further, if you look at some of the recent competition winners you'll note some have been new members to the forum. Certainly not the same people at all.

Can't you get some idea of value from recent eBay sales? At the end of the day, what it's worth is what someone is prepared to pay for it and that can depend on how you go about selling it! You could just let it find its own value on eBay or similar or a dealer may give you a good deal to sell a new camera (and sometimes not.)