I have just started learning Odoo/OpenERP, I am currently learning to create a wizard to display a list of items in treeview with a few fields, some are fields with already existing values, some are editable fields to modify the values of the existing fields. Due to the myriad of ways to code & multiple versions of APIs, I have gotten quite confused in deciding which ways to do this.

For example, we want a wizard to display a list of selected products in treeview through a pop-up window, we want to get the products from "product.template" object, along with the product name, product category, sale price, and a new sale price field.

Here we will get product name, product category, and sale price from the object "product.template"while new sale price will be a new temporary field to get input from the user, so that when the wizard do the method to apply changes, the new sale prices for every individual product will replace the sale prices of each products.

Please enlighten me,

What would be the best way to do this ? If possible, please show example of doing this in both the old API and the new API (for Odoo version 8). 

I would really appreciate your helping hands, and also awesome minds :)