Sorry..... conspicuous by my absence again......
I am quite happy with splitting runs over 2 sessions if time/situation permits or forces it, all I would say is that if the planed run is say 5 miles try to split it as 2 x 3 miles so you do a little extra, it is all about getting used to running on lactate stuffed legs as you will towards the end of the marathon.
Always a good idea to do a shortish run the day after the weeks long run again to clear a bit of rubbish out the legs and loosen them off. DOMS is then greatly reduced, well it works for me anyhow......
Nice to see if you can do some core work as part of your training, doesnt have to be an enormous amount but if you can do a bit to strengthen your centre it will help wth the support and posture whilst running.
Have you had any more thoughts on nutrition, whay are you doing feed wise at the moment........