1. Will unlocking the SIM for domestic US use cause any problems with using the phone on Sprint?
2. If I remove the SIM card does that basically disconnect Sprint service?
3. I am assuming that if I wanted to test out a different service say from T-Mobile ($30 Walmart plan), or any other subcarrier, after the phone is SIM Unlocked I would just get one of their SIM Cards and place it in the phone and do some activation stuff and in theory that should work. If that is the case would this cause issues at all with Sprint service?
4. Would I be able to swap out a SIM card from AT&T (or any other company) to test it out and if I decided I did not like the service I could just slip my original Sprint SIM card back in and it would be like nothing happened?