Ok I get it:
1. Can I use ecart to change the display of the powerstorecart, without adding any columns?
2. Can I use e cart to change the payment gateway provided by powerstore?
I suppose I have to do this by creating a new checkout page with ecart?
I do this with the checkout wizard of the ecart?
3. I want to use ecart to calculate some flat shipping rates. I suppose at the globals file I should not have fedex or ups activated, right?