I think you should try job shadowing at a local hospital to get a better feel for what it's like being a nurse. Try a med-surg unit, since it will give you a good overall picture of nursing. It is a very stressful job, and the schooling does involve a lot of memorization. I find that it's been both intellectually and emotionally challenging, going through nursing school
As for these questions:
How often do you have to clean a patient?
This completely depends on what area you're going into, but you're definitely going to have to clean patients at some point. It isn't really as bad as I thought it would be. Again, if you spend some time shadowing on a normal med-surg unit, you'll get a better idea as to whether this will bother you or not.
What field of nursing deal the least with that kind of stuff?
I'd say the fields of nursing that deal the least with this stuff would be administration, public health, or something like that, but these fields generally want experience. New grads are having problems getting jobs right now and pretty much have to take what they can get. So, it's very likely that you'll spend the first year or so at least doing that kind of stuff.
How much do nurses earn? (I know of someone who is a nurse and seems to be living very comfortably)
Depends on the area. Check out your local paper or careerbuilder website to get a good idea, since pay is often listed on these sites. New grads in my area start out at $18-23.00/hr.
What makes a nurses job stressful?
Too much to do and too little time, high patient loads/acuity, loads of paperwork, the stress of knowing a mistake you make can kill somebody, etc. To get really good insight on these, browse this website's forums or type something like "cons of nursing" into the google search engine, and you'll get a really good overview of this.
Is it physical or mostly mental?
Both. Physically, nursing is hard on your back and knees. You have to do a lot of lifting, and you're on your feet for 12+ hrs at a time. Emotionally, it can be very stressful dealing with dying pts, stressed out family, too many patient demands and not enough time, etc.