Can I still get everything I would normally get on an iPhone if its unlocked?

If I get an unlocked iPhone 5s and I want to use MetroPCS can I still download apps using the app store, get updates, use iTunes, etc? Will the monthly payment be higher than $50? Do I still get unlimited 4G?

An unlocked phone just means that it can be used on any carrier.

Payment amounts and type of service are dependent on your carrier, not on the locked/unlocked status of your handset.

Of course