You will have mattresses there, but don't think America comfortable mattress, think India, hard as a rock mattress.  If people have pads and want to bring them it is advisable for comfort sake, but if not, there are "mattresses" everyone will have.

If you want to bring mosquito nets you can, it will make sleeping a lot hotter.  If people feel better with a net, go ahead, I never use them.  Repellant is a good idea, but you won't need a ton of it, you will only need it at a certain time each day (evening).  I recommend the Burts Bees Bug repellant, that works great for me and doesn't have the harmful chemical Deet.  I do know that studies show deet is a bit more effective, but I like the Burts stuff better, its not harmful for your skin and smells like lemon.  Also, if people are really worried they can bring garlic pills, that keeps some bugs away (possibly teammates as well, but for sure bugs)

As for dress code.  Girls will need ankle length skirts everyday for ministry sites.  At the house knee length shorts is ok.  On off days where you go to the markets or touristy places girls can wear pants, ankle length.  I can't stress enough ankle length, showing legs here is like going topless in the USA.  So capris are out as are knee or calf length skirts.  I'm sorry, I know its a pain, but its how the culture is.  Guys will need pants for ministry sites and can wear shorts at the house and out at the markets on off days.  Indians dress very nicely, so its important that we look nice and presentable.  They value that, so they aren't going to want a Jesus that is messy, dirty, and unkempt.