Hi, there I have taken it upon myself to answer questions regarding this plugin since it’s creators are not very active here, nor do they answer their email actively.
1.
You are right the syntax is weird. Their documentation is vague.
I’m afraid you’d have to create a custom function for that. It’s easy. Just go to your theme folder, find functions.php and at the very end write a function like so:
function multiply_by_two($price){
return $price*2;
}
Then you can call it from any field within WP ALL IMPORT like so:
[multiply_by_two({price[1]})]
2.
You should check their variable products tutorial:
https://www.wpallimport.com/documentation/woocommerce/variable-products/