Is store bought iphone 4s sprt by Metropcs?

Without knowing what kind of problems you've had with your previous phones, it's impossible to say whether you're likely to have the same problems with an iPhone. What I can say is that, unless the surgery you've had affects your coordination or mobility in such a way as to cause you to be more likely to drop your phones, I can't think of any way it would affect them.

You should contact Metro PCS to see if they support the particular phone you were given.

There are lots of reasons you could be having those problems. If you're buying inexpensive Android phones, they tend to be under powered without much memory. They rarely provide a good experience for anyone who does much more than make phone calls and check the weather. Also, it can be quite easy to install malware on an Android phone. Again, your back surgery is not going to have any effect on your phone's performance.

You are less likely to have both of the above problems on an iPhone.