How to replace drop ceiling with drywall?

We bought this house in 2001 at that time it was 2 years old. Over time i see cracks on my 2nd floor (1st floor is ground level). I see that house has settled one side more then other at least more then 2 inches. We noticed this as I was renovating bathrooms which is one in each side. One side bathroom door is slanted as overtime it was not closing and i had to adjust the knob and gap between jamb of door and door is quiet one inch with a crack in corner on drywall. My question is should i be concerned and if i should what are corrective measures i need to take. Thanks very much for any advice.

I recently moved into a high rise apartment and need to hang some wall cabinets. The cabinets themselves weight about 20lbs and I'm thinking the stuff stored inside them will be around 40-50lbs. I know I need to mount these into the studs which I've been told should be metal since it is a high rise, but I'm not sure how to double check this? (I have a simple stud finder but I don't know how to check if the stud is metal or wood) I went to Home Depot and bought a pack of 2" metal stud screws, which is what I was recommended by the person working there. I just want to double check that this is ok and will actually support the amount of weight (~60-70lbs). I know that I need to drill a pilot hole before putting the screw through but is there anything else I should be aware of when hanging these cabinets? I have never mounted anything using metal studs. This is the suspension rail to which the cabinets are attached. [url=http://www.ikea.com/ca/en/catalog/products/10124585/]BESTÅ Suspension rail - IKEA[/url] This is the cabinet I am trying to mount, I have a single like this one and also a double which is two of these attached to each other and are all mounted using the suspension I posted above. [url=http://www.ikea.com/ca/en/catalog/products/S89032465/]BESTÅ Shelf unit with door - black-brown/Tofta high-gloss/yellow - IKEA[/url] Thanks a lot for the help/advice! :)