I have a dishwasher. Some might say it is excessive for a bachelor living on his own to have a full size dishwasher, but what the hey!
Anyway, your questions:
1) I cook a lot of curries myself (from scratch, none of this sizzle and stir nonsense). As Breezer mentions, the plastic inside does stain. The white plastic has now got a very slight pinkish tinge. It has no problem with fairly oily utensils and plates, provided you rinse the worst of it off first.
2) My dishwasher washes between 40 and 65 celsius. I leave mine on the "eco" setting (washes at 55 degrees) but I think it dries at a hotter temperature because the dishes are so hot that afterwards you need to leave it a long time before you can touch plates and not burn yourself (and I used to be a waiter, so I can carry VERY hot plates!) Some wash at 75 celsius, there may be hotter ones although I think 75 celsius counts as sterilising so any hotter wouldn't have much advantage.
3) Dishwasher capacity is usually measured in "place settings". A full-size domestic dishwasher is "12 places" which means it will take the plates, glasses and cutlery of a 12-person meal. This does not include pots and pans and utensils. I generally chuck everything in mine (even though you aren't meant to dishwash cast iron pans!). You could get everything for a typical three course meal for 4 in there I reckon, including pots and pans.
4) To maximise capacity, dishwashers have racks to make sure the plates are stacked in an effective manner.