Paprika would help his coat and you wouldn't have to give the little thing that much; here is a link to a thread I started a little while ago about it: Paprika for horse coat color enhancement?
A lot of people helped me out on the subject, so it should answer all of your questions!
I have never used it but I've heard that some people use bluing mixed in shampoo for the white spots? Someone else could give better advice in that respect.
Nutrition has so much to do with how healthy they are, and how healthy their coat will look, too. Does your pony only eat hay and grass, or does he get some grain and additives as well? Bioton is great additive to feed them and so is HorseShine. There are a lot of others too.
Show Sheen also helps to make horses' coats look shiny. You just mist it all over them.
Also, do you keep his mane long or pulled? Either way, here are some things I do for my horse's super long mane: Fructis Sleek and Shine leave-in conditioner is the best stuff, and I really like Cowboy Magic products too. MTG is a great product to really get the hair growing, but I warn you it stinks like old bacon! I know that most people don't comb out their horse's manes or tails a lot if they want them to grow, but I do it ALL the time. It is not with a regular mane comb though; I never use those. I love the Grooma Rake; it has teeth that spin so it does not tear any hair out, and it takes very little time to comb the hair out. It used to take me about 25-30 minutes to brush my horse's mane and tail but now it only takes about 10 minutes! Here is a link to it: Grooma Rake - Grooming Tools from SmartPak Equine
Pictures of your pony would definitely help also!
Last of all, here are three before/after pictures of my horse; you can see the huge difference that nutrition and "hair care" can make:
This is her when I got her: She was totally pathetic. 100_2540.jpg
A year ago: Big dif, and overweight! Gained some muscle tone,too. 100_5631.jpg
And here she is now: Had her lose a couple hundred pounds and look at how much her hair grew! Gained some more muscle tone also. DSCF2963.jpg DSCF2269.jpg