Simple Fix - PHP Search function, Inventory page, Add User

I have another simple project for someone experienced. This project has 3 parts. I will explain the parts in detail exactly what I am looking for. Before I do, you need to make sure you are able to perform the work. I want you to be 100% sure you can do the project in full. I need to be very specific in explaining the problem to me. Domain in question: [login to view URL] Part #1 -Fix the search feature of my website. -Located on /[login to view URL] page. -Basically, the search works fine if you specify what "make" and "model" of vehicle you are looking for. -I need the search feature to work even if NO "make & model" are selected. SO, if someone just wants to find a car between "$0" - "1,500", they would be able to do so. Usually, if a search is done, the information is sent to the browser address bar. Part #2 -There is an admin section to this website. -Included in the admin section is "add a user" -It used to work fine, and I was able to add users. Now when I go to "add a user" it goes to a blank page. Part #3 -Fix the inventory page. -It works fine. I know how to adjust the hmtl template for the page. -What I need is someone to figure out how to split the page vertically. -Right now I have the inventory set up to fill the whole page across. -What I want to do is split the inventory page in half. -I will adjust the template so the vehicles only take up half the space. -So if each inventory page has 10 cars listed. I want 5 on one side, and 5 on the other side. All of these parts must be completed in full. Make sure you know what you are doing. This is a very simple and easy project for anyone who knows what they are doing.