Nutrition during and after exercise question

Hey folks,
Exercise type: fast walking (3.5mph plus) on rough and varied ground for 15+miles carrying a light day pack
Duration: 8 hours (including lunch and coffee breaks)
For fun I've started to run gently on some of the downhills and other bits but not more than 1-2 miles in total
So - currently I've been drinking plain water, eating Nakd bars/Trek bars/Clif bars (maybe two bars in total, not two of each!) and have gels as a backup (although not needed often).
Lunch is soup/bagel and tofu sausage at lunch
Questions!
*should I be using a rehydration drink during the walks (I am a sweaty beast at the best of times)?
*If yes can I usefully stick with the low cal ones (I am actively trying to lose weight)
*post-exercise this time after 16.5 miles I used a proper protein recovery drink (normally I just have a 500ml carton of choc soya milk) and feel it did me some good in terms of how I felt afterwards. Any thoughts - soy milk good enough, should I add anything to it? Commercial recovery drinks any better?
Thanking you very kindly
PS the frequent long walks are in training for walking the coast to coast next year
Exercise type: fast walking (3.5mph plus) on rough and varied ground for 15+miles carrying a light day pack
Duration: 8 hours (including lunch and coffee breaks)
For fun I've started to run gently on some of the downhills and other bits but not more than 1-2 miles in total
So - currently I've been drinking plain water, eating Nakd bars/Trek bars/Clif bars (maybe two bars in total, not two of each!) and have gels as a backup (although not needed often).
Lunch is soup/bagel and tofu sausage at lunch
Questions!
*should I be using a rehydration drink during the walks (I am a sweaty beast at the best of times)?
*If yes can I usefully stick with the low cal ones (I am actively trying to lose weight)
*post-exercise this time after 16.5 miles I used a proper protein recovery drink (normally I just have a 500ml carton of choc soya milk) and feel it did me some good in terms of how I felt afterwards. Any thoughts - soy milk good enough, should I add anything to it? Commercial recovery drinks any better?
Thanking you very kindly

PS the frequent long walks are in training for walking the coast to coast next year
