RebeccainGA, I think you'd be okay with the salwar kameeze. As someone of Indian origin, I wouldn't find it offensive. Afterall, I wear pants, skirts and other "western" clothes almost exclusively.
The problem is that some items of clothing/jewelery have a specific meaning attached to them. Crucifixes, yarmulkes, native headresses, etc all special significance and symbolism attached to them. An outsider wearing them as just an accessory, or to be ironic, is well, pretty insulting.
I think that adopting another culture's style is okay if one takes a bit of time to research first. If the item is just an everyday article of clothing you're probably okay to wear it. It it has special significance religious or cultural significance, you might want to reconsider.
Head scarves, unlike the examples above, are not strongly identified with any one culture. Lots of cultures have worn head scarves for a variety of reasons from the religious to the mundane, so I think OP should be fine to wear them.