RE: Ghazis, I second Guitar Andy's approach, using predominantly WHITE for their clothing and turbans. In addition to sword & dahl shield armed tribesmen, I also have 3 x 20-figure basic units of Ghazis from Wargames Foundry Darkest Africa Baluchi Swordsmen, discarding the few in each pack with "Arabian" bare heads and using the vast majority dressed in "Indian" style, wearing turbans and beards.
Here's some pics of them in action over the years:
RE: Trouser color for "Punjabi" regiments... during the Second Afghan War there is no all-encompassing answer, at least in the nit-picky historically accurate sense. Khaki is usually right, but as with British line units, during this transitional period, some Bombay, Madras, and Bengal regiments wore blue or more rarely red or green trousers.
Unless you want to paint up a very specific unit, khaki definitely works well. Those Indian regiments that wore non-khaki pants mostly wore dark blue, such as 45th Bengal Native Infantry/Rattray's Sikhs, and 1st Bombay Grenadiers.
There were actually something like 18 different "Punjab" Infantry regiments which served in Afghanistan during the war. Some were Sikh regiments, so they wouldn't work with the Artizan "Punjabi" figures, but many of them were not. Off the top of my head I don't know if any of them are known to have worn non-khaki trousers. If you have a particular regiment in mind a Google search may be able to help. Also if you post the name/number of a particular Punjab regiment here I can check my reference books and try to find an answer re: trouser color. But if you just want nice looking generic Punjabi infantry, I would suggest khaki as the first choice, or if you'd like a spot more of color, then dark blue.