Website improvements

I currently have a website that is a combination of old school HTML, DIVS, JQUERY, and a whole lot of other things all smashed together ([login to view URL]). At the moment it works just fine, but I have another freelancer creating a self-contained registration system that I know is going to throw a few issues into the present design setup, so I need a few tweaks made to my existing website so it can handle the update... Firstly, you can see the new registration system in progress by visiting [login to view URL] I need my website to be updated to perform the following... 1. I need there to be a log-in button at the top left of the website that will populate a VERY tiny window (jquery or a floating DIV or a fancybox would work fine) that works with the log-in page at the above URL. It would also be nifty if when they logged in it said something unto the effect of, "Welcome Name!". 2. I currently populate most links on the navigation menu into the primary DIV on my website so that the page auto re-sizes and I don't have to deal with a frame and multiple scroll bars and all that jazz. I know that with some pages, depending on their content, it can mess up the primarily [login to view URL] file and make things look strange. If there is a way to make all content load into the website in such a way that the header and footer remain intact, in their present position, that would be great. 3. Right now when you hit back after going to a new page, it takes you to the previous website you are on, not the previous content in the DIV. I applied a temporary fix by putting back buttons on some pages but I know that this is rather inconvenient to the website visitors. I need that to be rectified please. 4. I would like it if the navigation menu, not the header but just the navigation menu, scrolled down as you scrolled down on the page. 5. Above all else, the button for the log-in, the subsequent window that allows you to log-in, and anything else you can/do implement MUST look like it's made for children. Please only bid if you have a sense of child-like design. Thanks in advance! Preference will be given to individuals that can complete the job quickly, be very communicative throughout the process, and who have a good sense of child-like design. I put in a budget for a simple project because I'm not sure what an appropriate price would be for this, but I'm willing to pay more for the right person.