Admission advice

Hello everyone,

I am looking forward to apply for MFE program in the US. I am 23 and currently enrolled in the Quantitative studies for finance program in Columbia and would like some advice for my application. My target schools would be: CMU, Columbia MFE and MAFN, Cornell, NYU, Baruch and Princeton. (Maybe I am aiming to high?)
1.- GPA:
This is my BIGGEST concern as I come from a non-well known university in Peru. I have a bachelor's in Civil Engineering and gpa 3.07 when using the WES service. I believe this translation is sort of inaccurate as I have been a top student for my 5 years of studies (I can elaborate more on this if you will, grading is certainly not fair in public universities in my country). Basically this is the reason why I decided to enroll in this Certificate program. On the summer I took Calc II,III,Linear algebra and Differential Equations. I got A+ in each of them, except for Calc III where I got an A. This semester I am taking Prob and Stat, Analysis and Optimization, Programming in Java and Intro to Data science (developed this curriculum with Prof. Mikhail Smirnov from MAFN program) and I am fairly sure I can get A's on them at the minimum. Additionally, I took some courses at NYU on Corporate Finance, Financial Accounting and International bussiness (Don't know if that is relevant). I plan to take the C++ certificate advertised in this forum after I get some knowledge in Java. Basically I will devote the first part of next year working, taking classes on Programming and advanced Prob and Stats.
I have already approached many admissions teams from a couple of universities (Columbia, NYU, will go to CMU NY campus in 2 weeks and will also try to set up a meeting with someone at Baruch) and they told me that their admissions committee acknowledge that the grading scale is different in every country, but I am afraid that since Peru is not really a well respected country in terms of education my undergraduate background will drag me down forever. Any advice on it? more classes to take? I am doing the Columbia certificate to show that I can do the work on math heavy classes. Again, maybe I should have taken more advanced classes, but cannot afford another semester at Columbia or US because I am saving for an eventual master's degree. I will certainly write something about it on my essay or as an extra letter.
2.- Job experience:
I have started my own business (family one: partnership with brother) since 2013, started working in a farm trying to grow pecans, and then starting their exportation to Asia and other countries. Since we have been fairly successful at it, we also started a second business of consulting which led me to work with many big companies and have a close relationship with a large US company (which has allowed me to basically live and study in US). I basically helped them export their products as well and have better profits. The important part comes when they did not have enough capital and I started structuring loans for them both in US and Peru. I have worked with many banks in Peru and all of this sparked my interest into finances. I want to develop financial products for the agro sector, go into risk management and scale my business as much as I can. My plan would be to go into wall street and work for a big bank in the risk management side and get plenty of experience, and then scale my own business since currently my Civil Engineering degree doesn't help me achieve that. I have always loved quant heavy subjects, so I believe and MFE program would be ideal for me.
My question here if it this is at all relevant for an admission for this type of program? (Maybe it looks better for an MBA, but I have no interest in that one atm). I am 80% sure that I will get an internship next year in Sao Paulo, Brazil and work with an investment firm. What kind of extra activities would you recommend me to enhance my profile?
3.- Recommendation letters:
I can get one from one of the executives from the US company that I mentioned before. (Basically they are all from Ivy League or top unis) and when I mentioned them my plans, one of them kindly told me that he could do it for me (Columbia alumni). I am almost sure that I can get another one from a big executive in a fairly big bank in Peru, but I don't know if it is better to get these letters from my ex-professors. I have read many comments here in quantnet and on NYU webpage that some students write their own letters and make their professors sign, or that they do no want letters from professors that taught basic classes. Here is my dilemma: In my former university almost nobody speaks English, I would have to translate their letters. I can get one from my dean but he taught me non-finance or math related subjects (highway design, structural design maybe?). I have very close ties from 2 professors from the Certificate that I am currently doing right know, but they taught me Calc II and III. One of them asked me to be his TA for Differential Eq, but Columbia does not take Post-bac students as TA's. What can I do here? I was thinking of doing a big project with the assistance of my professor of Data Science, relevant to Finance and then hopefully get a letter of recommendation from her. Or should I just ask one to my former professors back in Peru? Would it look suspicious? I certainly do not know how people from admissions of MFE programs look at South American students since I believe there are virtually no students coming from SA.
4.- Additional info:
Toefl score- 109
GRE score - 321 (166Q/155V/3.5AW) -> Will certainly take it one last time, got cocky with the quant section and made mistakes.
I will leave my consulting business aside, my brother will take care of it and focus on getting into an MFE program. Ever since I read about this program, I fell in love with it.
Self-study: I just bought A primer for the mathematics on financial engineering to gain more relevant knowledge of this program.

Thanks in advance, and any advice would be greatly appreciated!