Although English is increasingly widely spoken in Mexico, it would be dangerous to assume that all business acquaintances will be fluent in the language.
English language levels vary widely and it is best to check in advance that translators will not be necessary. It goes without saying that you will be at a great advantage if you speak good Spanish.
It is common for colleagues to address each other through the use of family names, moving on to first name terms only when the relationship is very well established. If in doubt about which name to use, it is probably safest to err on the side of caution by starting with the family name. In addition, titles such as Liciendo/a (a professional such as a lawyer) or Ingeniero/a (an engineer) are also commonly used terms of respect.
Emotion is not suppressed in business situations and discussions can appear heated and at times acrimonious to those from a culture which frowns upon any visible shows of emotion during business dealings. This outward show of emotion is seen as a positive and implies engagement and emphasis.
Mexican body language differs from North American and Northern European body language. People stand much closer to each other and have far stronger eye contact than in many other cultures. It is important that you are not intimidated by these issues, as lack of strong eye contact or maintaining too great a distance could be misconstrued as standoffishness or untrustworthiness. Try to mirror the Mexican approach in these matters.