Which branch of government do you think receive the most power under the constitution?

In theory, none. There are checks and balances that each can keep watch over the others.

In point of fact or practice, I would say the most powerful is probably the senate. There are 100 members and they can reach consensus easier than the house of representatives and they have more to do about writing laws than does the president. He has more exposure so he looks like he wields a great deal of power, but I think the senate probably has more power.

i really really really really really really dont know

since most of current immigration into the u.s., both legal and illegal, is coming from latin america. it would be very difficult to imagine or rationalize a country my fellow citizens are trying desperately to flee into, would pose a threat to my prosperity or freedom. since the u.s. has a long history of intervention, but no record of permanent occupation, i would not feel oppression is the main objective.  

the largest free trade nation, along with the largest gdp in the world wanting to expand it's economic policy on us, and including us, could only be positive. the u.s. government has no interest in, or way of simply forcing american culture on us. and has no track record of it. other nations that adopted american social culture, or "americanization" did so voluntarily, mainly through the choice of allowing american businesses and u.s. citizens to come into their nations, as free operatives.