I don't usually have problems with run of the mill cramping on my calves. Except in my 1st marathon, 12 years ago, I cramped badly after mile 23. I started out too fast, of course. I kept going by telling myself last marathon, HA! One of my problems was that an ITB issue kept me from training 3 weeks prior to the marathon. I didn't run once in 3 weeks. Fortunately, I had completed a 26 mile training run so I knew I could finish.
My understanding is dehydration causes basic cramps. Drink well and often. After a few races you'll know what you need.
Pain: advil, but I try not to overdo it.
Salt: I have noticed my fingers swelling mostly during hot/humid races. Some of the Gels contain minerals and I think gatorade endurance does too, but just to be safe, if I remember I'll carry 2-3 little salt packets and take 1 every 6-8 miles.
Water stops: I hit every one except maybe mile 25. I drink at least 8oz of energy drink. Toward the end of the race I'll sometimes drink 8oz of water too. I sweat more than most people. I'll easily lose 7 pounds in 1 hour on a hot summer day. I don't carry fluid unless I think the race won't be well supported.
A few years ago I was having trouble with tight cramps during cold races, sub 45 degrees. I was running 10 miles a day back then and PR'd. I started wrapping plastic bags around my calves to keep them warm prior to the race. After the first mile warm up I would pull them off. It seemed to help. Lately, I've noticed a few people, including Chuck Engle, wearing calf compression socks. Everyone I have talked to seems to like them.
I am still learning after 150 something marathons.
Good luck and Congrats on your finish.
