1. What powers does the National Emergencies Act of 1976 give POTUS ? "Trump can only use specific powers Congress has already codified by law, and he has to say which powers he’s using. The act doesn’t define what counts as an emergency."
2. What congressional power in the constitution is Trump trying to get around by declaring this? He hopes to get around their decision to not fund the wall.
3. How would Congress pass a joint resolution disputing the emergency? "Both chambers of Congress would need to approve the resolution by a simple majority (that’s 51 votes in the Senate and 218 votes in the House)." but "Because of his expected veto, stopping the declaration this way would require a veto-proof majority, which consists of a two-thirds vote in both the House and the Senate."
4. What action can the president take in response to the joint resolution? He could veto the bill they present to him.

5. Why would landowners potentially sue the president to stop the wall? They don't want any land to be taken from them in order for the wall to be built.6. What happened to the eminent domain lawsuits filed against President Bush? It was "reported that 334 eminent domain lawsuits were filed in South Texas under the Bush administration, and 60 to 70 of them are still pending."7. Why would the ACLU sue the president to stop the wall? He admitted that there is no national emergency that he is just impatient, so they want to sue because it is a blatant illegal declaration. 
8. How could states serve as a check on presidential power? If a states federal funds are activated then the states could resist and take Trump to court.