Forgot to mention your question about foreign "tax home", if this is the same concept as the bona fide resident of a foreign country.
Typically there are 2 way for US expat to get the 80+K tax break.
1. 330 rule / physical presence test
OR
2. bona fide resident
If you choose 2 as becomes a US citizen living overseas...In addition to the 330 day test, you also must past the "intent" test. i.e. you intent to live in a foreign country indefinitely and will not return to US any time soon.
bona fide resident is hard to pass audit if you are just an expat on a 3-5 year assignment overseas.
Please consult your HR and/or intl tax expert for more details.