Thanks so much for your questions regarding packing. So to be more specific on dressing appropriately for women, I would say that tank tops may be fine in some contexts (such as in urban areas) as long as they aren’t too revealing (we would recommend thicker straps). In rural communities and while on trek we will ask that students dress more modestly with shoulders and legs covered. In some setting leggings may also not be appropriate, so if you want to use leggings you should throw something on top of them like a skirt. Shorts are fine a long as they are not too short (mid to lower thigh length and longer). For hiking I would recommend things that are very comfortable that can deal well with both cold and heat (quick-dry material). The mornings when we start hiking are going to be very cold and around noon will be pretty warm, so pants that turn into shorts are a good idea if the zippers don’t rub your legs and irritate them.
Basically the same things should apply for men.
Hope this helps!