Question about iPhone unlocking, choosing operator and using the phone out of US.

Dear MacRumors users,

I'm going to USA this summer for a Work&Travel Program and the first thing I'm doing when I arrive in Michigan - is buying an iPhone 5s 32gb for myself and as I'm not that used with iPhones - I would like to ask you some questions. By the way, I'll be staying in the US for 4 months. From the middle of May to September.

As I read - there is possibility to unlock the iPhone by IMEI, so here comes the first question:

1. Should I buy the unlocked iPhone and SIM card separately so I could use the phone in my country (Republic of Moldova) with my native carrier - "Orange" for $750 when I come back? If yes - what operator would you recommend me for the light purpose (to be available on the phone, light amount of calls, a little 3g data)?
2. Or should I buy locked iPhone for $300 and pay extra ~$50 to unlock it? If yes - what operator is easier and less complicated to unlock? Or I can unlock it only after ~6 months?
3. Due to the above - is the next idea possible to implement: buying iPhones, unlocking them for total of ~$350 (if talking about 5s 32gb), sending them to Moldova where they are being sold for like $800+. Profit?
4. And finally, if there's no mistake above and all of this is possible - do the IMEI's on the sealed package and the iPhone itself always match so I can send the IMEI to unlock without breaking the package itself?

Alternative suggests are welcome.


Thank you for your attention and help in advance and have a nice day. :)