Some people do take cameras !
I remember Slotwin saying a Marshall thought she was wearing earphones (it was in fact the strings of her hat) so the no mp3 rule is enforced (although the roads are closed, there are still bail buses and some roads are pretty narrow).
On a purely practical basis any electronics would need to be in a waterproof bag, ziplock bag from Tesco would do. It gets hot and people squeeze water over them (I.e. even if you didn't, there would be splatter from the nearby runners). I did take my phone in my belt this year but it was in a baggie and, apart from a start pen photo, it didn't come out until the finish. All my energies were going on reaching the finish safely!
I don't think taking a phone or camera out for the odd pic would be a problem as long as it was out of everyone's way.
But back to sports watch stuff.
For Comrades TBH a ??10 watch will do - you don't *need* a GPS.
Because the markers are in km to go, you just go, (for example)
* the time is 15:30
* I am at 21km to go
* I therefore have 3h to do 21km in
* I will be OK but can't walk yet
* time is 1530
* @17km to go
* I can walk to the finish
That said the 310xt is cheap now and has battery life to spare - mine is over 3 years old and still lasted through an 11:46 Comrades (uuurgh).
I help run the beginners courses at my club. Post exercise soreness, when you're using new muscles, is normal - by that I mean the sort of feeling you get after a spell digging in the garden or ceiling painting. The feeling is worst 2 days after and then goes away.
"Battered" and "agony" sounds worse than that. I wouldn't give up, as running has a lot to offer. Instead, try something (up to you - swimming?) different for a few days until you feel OK again - keeping up the exercise routine, you see, even if the type changes - and then start running at the last c25k week you did happily, and if in doubt repeat weeks until you are sure you can move on to the next one OK.
If you look on the beginners threads, you'll see that repeating c25k weeks is not at all unusual. And in the longer run, successful and happy runners are those who listen to their bodies and do the training that works for them - trite but true(!).
Oh and if the problem persists - not feeling better in a couple of weeks - you might want to check with your GP in case some old injury or issue is being brought to the surface by the new activity (again, something we do see)... and you might want to go to a local running shop and see if they have shoes you miraculously feel better running in (a proper running shoe shop will let you run round in the stock).
PG3 - never heard of an international not being able to use a particular marathon or ultra for qualifying.
Pen doesn't make a huge difference - it's just one small factor over a very long day - 2-3 mins...less than the time lost if you walk a mile rather than run it (and it's not unusual to be walking a lot late on!).