Sir,
2 Pollution with dirt and chemicals is there ,as much as it is there in most countries of the world.I don't get it what you meant by dead human bodies?Where ever there are human ,there will be some dead also,rule of the nature.But we do not place them on display in public as you seem to assume.Dead animals,again its not that on every nook and corner you are going to see dead animals,It is as common as it is in most of the world.
3 Superstition,Even i do not believe in it .But since you are refereeing to Hindu religion ,I must clear it to you that it has a rich cultural and spiritual heritage ,things mentioned in our ancient text and ideology cannot be just written off ,there are reason for every act.And one you are stating as deformed being are our "god" least you can do it ,is to show some respect.Nobody is forcing it on you, follow what you like do not follow if you don't like.
4 Caste system ,as i have said earlier do not go around as touting urself as untouchable and you will be fine ,and even if you say that you are untouchable you will be fine with the youngsters.You are Roma describe urself as one, no need to go in details.