Well, I will give you my personal opinions and experience (may not be much use but o well
).
I generally try training ALL of my show horses to jump when they turn 3yrs. I generally determine where they would fit by how well they like to jump. My horses that LOVE to jump make the best jumpers because they are willing and fly over the jumps and can just keep going all day. Very important to work on teaching them not to leave you behind though as it can knock your time down if you have trouble turning. My hunter horses are willing to jump because they want to please me but that makes them a bit slower pace, more in control, and easier to paint the "pretty picture". And of course there are some horses that do not want to do it at all and I have found that those arent worth forcing to do it as they wont do it as well as the ones who do. Hope all that made sense :-D
In jumper it is all on speed and clear rounds. Hunter is collected and pretty (think showmanship).
Tack is just a regular western or plain leather halter. The arabian style halters are not recommended as they are fairly fragile and the chain can accidentally bump your horse when they go over the jumps.
I show both my hunters and jumpers with braided manes and tails, it just gives them a more finished look and its fun to do
....not everyone braids but prolly 50/50.
Trotting in Hunter just is easier to maintain the pretty look. It is very important to keep a constant gait. It is not pretty to walk to and from jumps because it is harder for the horses to jump at that slow pace and can take away from the look running like a madman to keep up with a loping horse
.
My hunter horses: I think both pictures might have been taken during their jumper classes but both are currently more into hunter.
Magnum (he has potential to do jumper too if I get him fit up enough this year, has great form and speed, but can easily be slowed down for hunter)
Pearl (did really well the one year I showed her hunter and won at the National Area 6 show, plus brought her out fat and broodmare looking last year and she won again!)
I am by no means an expert, just really like these classes
, hope this helps some!