I think my reply is too late to help with your graduation problem (sorry hope it turned out well) but I thought I'd post a reply anyway in case anyone else is looking for a similar answer.
I straightened my hair for years before discovering the CG method. I picked up a lot of advice from great stylists and trial and error over the years and even though straightening wasn't good for my hair, I think I did my best to minimize the damage from excessive heat styling.
For years my method was to wear my hair curly on wash day, then straighten it the day after. I absolutely have blow drying my hair (I'm so impatient) and my hair will not blow dry straight. I have to flat iron it after blow drying or it is just a giant frizzy blob. I have tried different brushes, different products, this has always been the case for me. I have very coarse, high density hair. I'm not sure if different hair types have better luck with blow drying. Because I don't like to spend a lot of time on my hair, I always left my hair curly on wash day, with leave-in conditioner and mouse in my hair. Then 2nd day I would comb a leave in spray and heat protectant through my hair (not enough to make my hair wet, I agree you should never try to straighten when wet, it makes your hair very crunchy and stiff or else frizzy).
I used a Le'Angelique ceramic flat iron. Any ceramic flat iron will probably work fine, I just love the Le'Angelique because it has full ceramic plates instead of ceramic coated and it has lots of heat settings (also heats up very fast). However if you are not planning on straightening your hair often, you definitely don't want to make that kind of investment. If you can borrow a ceramic flat iron from someone that is best.
My favorite stylist ever (who moved away and made me sad) told me that it is better to straighten you hair on a high heat setting so that you only have to run the iron through your hair once. My hair is coarse and will not straighten below 375 - 400 degrees. Finer hair can probably do fine with a lower setting. If your hair is fine, I recommend starting around 300. try it on a section of your hair and if it does not straighten fully then turn the heat up. The more you run the iron over the same section of hair, the more damage you will you (increase the chance for breakage etc). Don't clamp the iron down too hard on your hair either and pull the hair out away from you head rather than pulling down.
I would wash my hair every three days (1 day curly 2 days straight). The extra oils and product in your hair on day 2 help protect your hair from the heat as well.
I finally decided to go curly and found the CG method because I moved from the dry southwest to the humid midwest. My straight hair just couldn't handle the humidity and I was unhappy with the way it looked. Honestly I miss my straight hair (I think it suits my features better and I like being able to touch my hair). If you are in a humid area then you will need a good shine serum or anti-humidity serum. It can make your hair feel greasy and weighed down sooner, which is why I didn't like to use one (I really don't like to have to wash and do my hair often), but for a one time straighten is probably your best option (makes your hair shiny like a commercial too). If you are really only going for a one time straighten, then I recommend borrowing your flat iron and products from a friend. If you are looking to straighten more often then definitely invest in a really good iron and some good products.