Looking to get a Droid, live abroad and travel to the US - Help!

[Tutsumi]

As the title states, I'm looking at switching over from my iPhone4 to a Droid since my current telecom provider is going to LTE/HSPA in a few months (HSPA+, both Upload and Download plus they did a LTE test just yesterday).


I'm looking at perhaps a Galaxy S II I9100 but I'm not certain about it due to "international" usage. Here's my situation:


Currently we are supporting GSM. Some people are saying we need 1800 MHz, but a lot of sites are saying 1900 MHz, then again most phones cover this.
As I said before, we're supposed to be getting LTE HSPA+ in a few months, something the iPhone doesn't even have yet. I'd like to use a phone that could use this.
We don't have AT&T, Sprint, Verizon, etc. down here. Are there any phones (like the GS2) that could work down here once "4G" is introduced? I ask because I saw people saying how it would only be GSM, etc. etc., and I'd like to make sure it's actually so.


Thank you for your time!
(Also, the local and only telecom we have down here is the Bahamas Telecommunications Company aka Batelco aka BTC. It was recently bought out by LIME, if specs are needed.)


Once again, I'm looking to get a Galaxy S II, but not sure which one to get for what I need. I am free to other suggestions on a phone though.


P.S. One more question: What's the difference between Unlock and International?
I see Unlocked here on Amazon saying, "Samsung i9100 Galaxy S II Unlocked GSM Smartphone with 8 MP Camera, Android OS, 16 GB Internal Memory, Touchscreen, Wi-Fi, and GPS--No Warranty (Noble Black)"
I also see it saying on another listing, "Samsung Galaxy S II GT-I9100 Unlocked Phone with 8MP Camera and Touchscreen - International Version (Black)"


Also, which version of the Galaxy S II should I get?