Toes: Assuming you don't need to wear your running shoes, and have some other shoes which don't rub the same places, then for now, I'd aim to leave the ripped areas on your right toes undressed, so skin can dry out.If you need to dress, then you'll have to remove dressings before shower / bath to avoid sogginess, which means skin gets damaged a bit each time. If oozing a bit, then, assuming you can keep feet clean ie indoors, not in a muddy field, then I'd leave them uncovered, wearing sandals only. I'd try injinji toe socks for race, washed once, not worn straight from packet, assuming skin is in OK state by start of marathon.
Insteps: again, if possible, leave uncovered if you can keep them clean. Skin will dry and can be trimmed off in next few days. As blister will probably reappear during marathon, I'd suggest getting some film dressings eg Tegaderm to place over area, covering generously, but without creases, so you'll probably need to extend round both sides to top of foot - much less likely to peel off if the edges are in non pressure areas. You will probably need to trim a large dressing, originally eg 10 x 15cm, to 5 x 15cm and trim corners so all are curved, like the originals.
Lacing: a question of experimenting, but often a single overhand knot, to keep lower foot lacing relatively tight, then continuing lacing for rest of foot and tieing at ankle, can work well, Many shoes have double holes at ankle, so you can double back and have knot at 2nd from top holes.
I don't work for Accelerate running shop in Sheffield, but do know several of those who do, through friendships founded in volunteering at / competing in adventure racing, fell running, navigation challenge, adventure film festival etc. So, this webpage may help you:
http://www.accelerateuk.com/magazine/article/61/Injinji-socks---tested/
Plus a couple of articles about foot care for adventure races, which often include many hours of running, usually not on roads:
http://nyara.org/athlete-foot-care/
http://www.planetfear.com/articles/The_Hardcore_Approach_to_Foot_Care_607.html [be warned, lots of gorey photos]
Are you doing 18 miles or 53 miles of LDWA White Cliffs? You've got time to get the right shoes, socks, lacing combination by end August. Remember to only buy shoes in afternoon, when your feet have swollen from morning minimum.You'll need trail shoes, rather than road running shoes, and expect lots of shortish ups and downs. Many people use walking poles on such challenges, so might be worth considering.