Obviously double check with your doctor once you get everything straightened out, but I have seen most people say that you aren't really supposed to lift things that are more than about 25 pounds. As for the chemicals, I would try to stay away from them as much as possible, as commercial cleaning chemicals are usually much harsher than home ones.
Would it be possible to speak with your employer about your concerns? I think they are supposed to make accommodations for you, but I am no legal expert.