Reality Check on Data Roaming and Tethering in Ireland/Poland

I am in the U.S.

I would like to be able to go to Ireland and Poland and be able to tether my laptop to some kind of MIFI-like device or a cell phone that can create a wireless hotspot.

From what I've read here, this is going to be expensive if not impossible.

1. It's cheaper to get a SIM within each country for GSM phones.
2. GSM phones must be unlocked.
3. If I buy a phone here in the U.S. with an eye toward International data use, I may be able to do that, but it won't be inexpensive and they may not let me tether at all.

What I'm asking for is a reality check on the three statements I've made above.

And, of course, any ideas on what I might be able to do to accomplish the goals. :-)