Customization of Joomla template and Component

Hello, i'm new at this so please bear with me... I recently downloaded a freelance type joomla template that acts the same as this website or elance or rentacoder, but as I expected, it needs a lot of customization. I am making a list of all the detailed things i want changed but the big things that i can think of are: 1. Adding more payments systems 2. Allowing a user to sign up for both buyer and freelancer (currently not possible). 3. Adding different types of currency. These are the major things that i want fixed on the template's components. The template has a lot of bugs which are not major but really annoying. Basically if my site could have almost or all the features that getafreelancer has or elance I would be very happy. For now i've entered the smallest amount that is allowed for budget and I would like to know what could be done for that value. In advance: Thank-you.