Tiny Joomla edit and adding PayPal in chronoforms

Hey everyone, basically when it comes to the scripting side of things, im left clueless. I had someone create a fully functional Joomla site for me about a month ago and the thing i missed out on was Paypal; it wasnt in our agreement that he would add the payment form. He made 3 different enquiry forms using chronoforms, one of them is an order form and i need someone to modify this form. I need you to edit it first of all, because there are some slight defects in it which i couldnt fix myself. and i need you to add a miniature paypal cart; possibly one that uses jquery to add up the total cost of the items. The site sells services, not products. and there is a checkbox list where the customer can choose to have one, or more of these done so we do need the java. and i need you to explain how this works because from what ive searched, it talks about having a Paypal Api enable account? not so sure what this means. anyway, the other thing i need is for you to change a few lines of code in joomla so that my users are unable to create usernames and login with an email address, not a username. I can post this elsewhere so dont throw a big pricetag at me, it'll probably only take 30minutes of your time. i will ignore your message if im not satisfied with your price. It shouldnt even cost me $30 so i would actually like for you to have a look at my site, and tell me some things you could improve on for an extra small cost. The site is [login to view URL] its still in the demo phase so there is dummy content lying around. This is really something any of the freelancers can do and it focuses on script, not presentation so to let you know, I really am aiming for the lowest price. If your bid is below the $30 mark, i can always pay directly through paypal. Here is something i would actually like you to give me individual quotes for. Calculator(s). If you take a look at my site you'll see that the calculator section is in development. I need one done as soon as i can get it done. Im sure they all use the same type of basic code, they just have different values in them. I think they call it an Ajax Calculator with jquery? I downloaded one off another site a long time ago so ill attach that and send it to you if you quote me on this. Can you take a look at it and give me an idea on how long itll take to make something like it and how much you'll charge, etc... I eventually want four calculators created but give me prices for one calculator and all four calculators. Sorry for the poor description. extra: i will pay you on completion as i have experienced some difficulties in the past. Thankyou