usually the best way to go orange is to bleach for a short time on dark hair.. you just have to watch it like a hawk and rince it at the right moment..its nice cause it wont fade :P
the only other orange ive done was punky colors flame, wich is mostly orange with a hint of red.. i hated the color on myself but it lasted ages (figures, right? XD)
I used Manic Panic at first. The purple didn't really take to my hair (it looked like Halloween spray on). The black didn't really come out black, more red/purple. Didn't know black could actually go wrong.
I would suggest getting neutral protein filler as well, and as has been said, bleach first.
If you want a long lasting hair dye, check out "Pravana". I use it all the time and it's basically permanent. You'll need bleach to get it out and sometimes that doesn't work well. I'm good with hair products, I work in a salon and come from a family of stylists. Manic Panic can suck it hardcore
it really doesn't matter as long as it's as long as the bottle says. you can leave it on as long as you want-but it only makes the color darker which can sometimes make it lasts longer....
i've left special effects in all day, then the color washed out like 2 days later...
I'd recommend using a colour darker than the one you want it to be (so it'll fade to a nice colour). Also put the dye on and then leave it in overnight (to stop shit getting everywhere wrap your head in clingfilm). This is what I do and I've only dyed my hair twice in the last 9 months.