The full rules for the weekly comp are here

Yes, one can't expect to win a competition one hasn't entered, other than lottery scams!

What can it do its F & FA predecessors couldn't/can't?
I'm sensing the Emperor's New Clothes theory at work here!

Are you suggesting they should stop entering too?

It's more of a focus barrel than a ring, and it doesn't rotate during AF.

The 100mm macro tends to left on my K-1 ready for anything unusual that turns up in the garden!

Can't remember if it was advertised as such but yes it does and the PF review page (link below) says it does. It was actually advertised with 'fixed rear-element extension (FREE)' but TBH I didn't understand what that meant and still don't!
Also has a focus clamp to stop it quick shifting! Often with macro you want to fix the focus and move the camera to get focus otherwise you're chasing everything, both the subject and the focus. This is why a fully manual macro without AF isn't a bad option.

Reviews and details here:
https://www.pentaxforums.com/lensreviews/SMC-Pentax-DFA-100mm-F2.8-Macro-Lens.ht...
http://kmp.pentaxians.eu/lenses/short-tele/dfa100f2-8-macro/

Another bonus is it takes 49mm filters if required. A con is it isn't WR like the newer one but doesn't cost as much as that one either.

Can recommend the SMC Pentax-D FA 100mm F2.8 Macro (mine's the non WR version.)
Goes to 1:1, FF compatible and the Pentax ring flash is designed to fit on it. And yes it can be manually focussed.
It's such a great lens I've got two of them! (Open to an offer for one of them!)

You may find you can manage very well with a very basic fully manual macro too if funds are limited. (eg Vivitar 100mm/F2.8 macro )
https://www.photo.net/discuss/threads/vivitar-100mm-f2-8-macro-or-attack-of-the-...
http://www.fredmiranda.com/forum/topic/915389
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/45192-vivitar-...
I can vouch for the quality of that one.

You can always say it was ICB (Intentional camera blur.) It'll be alright then!

Yes it does have that with settings for up to 20 lenses.
It's menu item 27, AF Fine Adjustment, in the C4 menu.

An example image showing the issue would still be useful.

Still time, just, for your entry!