1. Egypt is in favor of the Gaza blockade because they don't want to stir up anything with the Israelis and thus the Americans.  The geopolitical realities are that Egypt is playing ball because there isn't enough a big enough movement in opposition that would cause them to act otherwise.  Make no mistake... The countries in the ME are out to do whats best for themselves first and everything else comes second. 
2. The U.S. government supports Israel for a variety of reasons.  One is because of its strategic importance in the world as a sector where American offensives can be launched if any Middle Eastern government does something we do not like.  The other reason is that if a public official ever were to make a statement not im support of Israel, Israeli PR campaign would begin targeted against the American official claiming such things as he or she is an anti-semite and so forth...  As in any political race, the funds go to the candidate who represents your interests... If you are not for Israel then funding goes to your opponent and you are left with slander campaigns against you...

Isn't it sad that another country can have that much influence in ours?