I want to customize the E-C ommerce module, change the title Price(default, set by the API) to "Fund Needed"

Hi All:
I am using E-commerce's donation module to develop a module for my website: a module for kids to post their social projects so that non profit can donate and fund for the projects. Basically i want to allow users to add "products"(whose type is donation), and allow others to come and donate for those "products". However, since this is for kids, i want to change the title "products" to "projects", and the title "price" to "Fund Needed".

The page for users to fill in information about the "product" is http://mygivingpoint.org/node/add/product/donate. And i want to make changes to this page so that kids dont get confused. i already used CCK to add more fields for them to fill in. but i have no idea how to change the other things which are already there.

So my questions are
(1) which file i should go to to change the source code?
(2)How do I update it? is that true once i change the code, the contents are immdientely changed or i need to do some steps to make the updates effective?

Thank you very much!

Also, i want to change this: on the first page, users are asked to click on the type of product they want to create, can i change the name of the type "donation" to "project"?

thanks!