Where do I find stats on impact of legal AND illegal Mexicans

[Felix Mala]

on our economy? My boss is trying to say it's the end of America if we don't stop Mexican immigration -- both legal and illegal. He's talking about Texas becoming a new white minority state. He says they move into neighborhoods, don't pay taxes and move their extended families up here. Then, when housing value plummet, they buy up the cheap houses. He also says they use up all of the Medicaid money and welfare and don't pay anything into the system.

I thought everything is really the opposite of what he says. That they do pay taxes, but if they're illegal they don't get benefit of those taxes. Also, that they contribute a great deal to our economy. Where do I go for the facts?