How do I insert checkboxes? How do I link them to data validation and vlookup?

Please see the attached example. The Order Form is populated based on the customer's answer to the question of how many computers they need service for. You will see the Data Validation for the question drop down menu, and the VLookUps for what populates the Product Price for each item based on their answer to the question.

1. I need checkboxes in the three places that say 'CHECKBOX'. How do I create these?

2. When an item's checkbox is checked, I would like it to put the Product Price for the checked item into that item's cell under Your Order Totals. When it is unchecked, I would like there to either be a 0 or nothing in that item's cell under Your Order Totals, whichever is easier. How do I do this?

3. It is mandatory that the customer purchases a Spyware Installation Package with their Service Package. Therefore, I need the checkbox next to "Spyware Installation Package" to automatically be checked and the Product Price populated as well as the Your Order Totals, based on their answer. If the customer would like the "Deluxe Spyware Installation Package", when they check the box next to that and the price populates under Your Order Totals, I want it to automatically uncheck the box next to "Spyware Installation Package", and unpopulate that price.

Any help that could be given would be so helpful!