I've heard not to do an MBA straight out of undergrad; in fact, the very top programs don't allow students to do so. Some MFE/MFin programs do take students out of undergrad though.
What part of economics are you interested in? If you're interested in macroeconomics, something in the...
Have you taken atmospheric physics classes? Aerosol research might be something that interests you in general - maybe check that out. It's also a field where people don't really know that much about how it affects temperature of the Earth (really huge uncertainties) so there's room to make progress.
Typical Wednesday:
Wake up at 7.30am. Study and grab breakfast until just after 10. Class until 12.30 - have an hour long lunch break (but have to get to the other side of campus). Lab class until 5pm. Run a meeting from 5-7pm. Might tutor for an hour or two after the meeting. Do homework until...
You sound a lot like me - I'm a current student and I'm also thinking of future careers. I don't know too much about engineering, but some kind of quantitative sales or marketing job might suit your skill set and interests. Some of my friends are going into science policy if they can get jobs...
Math was my worst subject in high school but physics was always my best. There are many different kinds of theoretical physics, and you might find that some sort of theoretical applied physics or computational physics might suit you better than string theory or something along those lines.
My school has a combined BS/MS in math, and my friend went to apply for this program and was told he needed straight As in math (no A- grades). He had straight As in math, so it worked out fine, but the expectation for a lot of math graduate schools is that your grades should be near perfect...
Do people know if unofficial scores given at the GRE testing site often change when you're given your official scores? I took the GRE today and my unofficial scores were good, so I'm really hoping they don't go down!
I'm not really into plasma, but one of my friends who wants to do plasma has raved about Princeton's program and is desperate to get in there for graduate school. Hopefully someone who's more qualified can help!
I'm not sure about software engineering, but the range of salaries I've received for internships have been between 1000 dollars a month and 1.5k per week (+ housing and travel bonus). So it's definitely within that range...
Tec de Monterrey is a university though - 1.5 years is enough to transfer to an American university, I think. In any case, why are you so sure that you're going to be admitted to MIT? Have you topped Mexico in any significant academic competitions such as olympiads or high school leaving exams...