Fine tune existing website

[login to view URL] It's a website that I had made to allow simple and easy uploading and downloading of files for people. Please check it out before placing a bid. It is live and for the most part working, yet needs fine tuning as there are many aspects of the website that are not working correctly. The obvious things that need corrected are: -Compatibility with all browsers and operating systems they are running on. Right now the site doesn't work well on some browsers. Obviously the most important ones are Chrome, Firefox, Safari, and IE. -A working file upload transfer status bar. When uploading a file, a realtime status bar that shows what percentage has been uploaded so far and an estimated time remaining. This is already implemented, but does not work all the time (not on all browsers, and has issues with bigger files). -Bigger file support. The site seems to work pretty well right now with small files, but has problems with bigger files (over 50MB). I want the site to be able to work with file sizes as big as a 5GB if needed. -Overhaul on the admin section. I need to be able to easily change the settings I want the site to use. Again, there is already an admin section to do this, but it doesn't work 100% and isn't the easiest to use. -Better system for me to be able to see how many users have signed up, how much bandwidth and storage they are using, etc. -Overhaul on most of the pages of the website. I like the homepage and like the current design and layout, but once you actually start using the site you'll see things that look cheap and poorly designed. Most of this stuff is common sense. Bottom line, imagine you were using the site yourself. What would you like to see on there and what functions would you like to have? I shouldn't have to point out everything that needs updating or looks bad. I just want the site to work, look pretty, and be simple to use. That's it. If I award you the project I will give you full CPanel and FTP access to the site and you would be free to work on it as much as you want so you can see what works in realtime. Even though the site is live right now, it's not really being used by anyone so feel free to work and make changes on the fly. Obviously, when you are done you will still need to send me all files needed with instructions (incase I have to move the site to another server).