Hi,
Yes, if you got an 800 on the GMAT, you will have such a high score that you should not have any problems getting into a business school of your choice. As for the IQ-GMAT score correlation, I have not come across any data on this. While yes, I'm sure having a higher IQ helps, I would not even take this into account. Many people with high IQ's take the GMAT, but that will not carry you through at all. It is integral to get in a good 3 months of prep work. If you need a good adaptive course or want to try at a free trial for one that includes a free sim test and tutor session, and a weeks access to the coursework, click here
https://gmat.economist.com. You can take the GMAT as many times as you desire. Yes schools can see how many times you have taken it, some take this into account while others don't. Usually retaking the exam is fine as schools are generally more worried about your score. With that being said, don't take a GMAT every month until you get a score you are happy with. Rather, try to prepare the best you can and get a good score without having to retake many many times. I would recommend contacting the schools you are interested in to see what they are looking for in a student. Not all, but many will provide you with this information. If you are not taking the GMAT for 2 years, this is to early for you to be starting a prep course or any intense GMAT studying. If you want you could go out and get some books on Quant and Verbal (grammar) basics. Try and familiarize yourself with these basic concepts, this way in a year or so's time, when you are ready to start your prep work, you will be able to jump right in without a problem. If you have any other questions please feel free to ask.
Sincerely,
Evan