Hey Eleni, welcome to the 20's board. I'm glad you decided to post. You definately are not alone in your fears, but let me see if I can help alieviate them....
"I fear this won't work for me" - It won't. Your RNY by itself will not keep the weight off long term. Initially there isn't a whole lot you can do to stop a good percentage of the weight from coming off, but it is going to take effort on your behalf to keep the weight off. This is a good thing, really. You are not dependant on something you cannot control to keep the weight from coming back. You, your own self, can largely control your weight destiny. This is the time in your weight loss surgery journey when you can really work on yourself to make changes that will help you for the rest of your life. Develop healthy eating and regular exercise habbits. Follow up with your surgeon and doctor. Get a support system by attending local support group meetings if you can and by allowing others around you to help and support you. Find a way to stay accountable, either by keeping a food journal or getting a good friend to keep you accountable. If you do your part, this WILL WORK. You can do this.
"I fear that I will not be attractive when/if I lose all the weight" - Look at Rianne's post-op pictures. Look at Alex's post-op pictures. Look at Jaci's pictures. Look at SheShe's pictures. Look at Kendralynn's pictures. Look at Jennifer's pictures. Look at SKennedy13's pictures. These girls are stunning. Honestly, go look. Now they aren't naked in their pictures, so I imagine, like me, they have some extra skin, but they are all beautiful, and I'm not a guy or anything but I think they are very attractive (Mike, Brock, guys am I right?). You know what I think it is that makes them beautiful more than the weight loss? I think it has a lot to do with how they view themselves now. They are more confident. They are more assertive. They are proud to have pictures taken now. It is an attitude adjustment just as much as a weight adjustment.
"I fear I will never get enough water and protien in" - Some days, and especially early out, you may not, and it isn't the end of the world. It gets easier with time and it becomes a habbit. What you need to concern yourself with is making a serious effort everyday to get as close as possible to your goals. Sip all day if that's what it takes and make sure you have a serious protien source in every meal/snack you eat and you will make those goals. I gets easier.
"I fear that I will have nasty loose skin and lose all my hair and go bald" - I have loose skin. I weighed 300 pounds and now I weigh 130 pounds, there is no getting around extra skin. It happens. But, I look damn good with clothes on and with clothes off I look damn better than I did at 300 pounds. Surgery is an option down the road to get excess skin removed, but it is time to dwell on the bigger picture here. WLS is not just to make people thin and beautiful. It is to make them healthy and vibrant. So if you have more energy, mobility and health as a result of your surgery, I think having a little more jiggle as well is okay in the scheme of things. I lost hair, about 1/3-1/2 of it all together, but I also was sick for a long time and that didn't help. You will lose some hair almost no matter what you do. Get your protien, take your vitamins (maybe add biotin, which helps with hair and nail health), drink your water and that is the best you can do. The hair loss is temporary and it will grow back. Think of it as a minor setback at worst. You aren't going to go bald.
You aren't the only one who has these fears. You are perfectly normal. When these fears crop up try to look at the big picture. You are losing weight to get healthy, and it is going to take a life time commitment, but if you do your part it will work. You are going to have extra skin and some hair loss, but that would likely happen if you lost the weight any other way, and it really isn't that big of a deal - really - when you look at all you will gain, all you have gained, some excess skin that can eventually be surgically removed if it really bothers you that much - isn't a big deal next to the years you have added to your life and the abundance of life you have the potential to exerience as a normal-sized person. I really hope this helps put some things in perspective for you.
Amy 293/140 - AT GOAL! 
LOL - and they totally are. 
