If your promotion isn't working after you've saved your promotion, you may need to close your internet browser completely (or open a new internet browser) for the promotion to take affect (you need to do this because your internet browser will cache the old promotion, closing the browser will remove the cache).
No. You have to have a separate code for each promotion or no promotion code at all.
Yes, flat rate shipping is under Store > Promos. When setting up a promos, in the Discount section, select Shipping Promo Type to be Flat Rate.
Eligibility for promotions when using the 'order total' is based on the order total before any promotions have been applied. If you have a shipping promo, the eligibility for that promo is calculated before any other promo discounts (such as club discounts).
Let's say you create a Promo for $70 off when 3 bottles are purchased. Each bottle is $35. We would expect to see 3 bottles as $35 since ($35 x 3 - $70 + $35). But it’s showing up as $35.01.
Here’s why: Since the $70 needs to be distributed across 3 bottles, it will calculate for $70 / 3 = 23.33333, which is rounded down to $23.33. This is why we see the total of each bottle at $11.67 as it is $35.00-23.33. The next calculation the system will perform is $11.67 x 3 = $35.01.
So the discrepancy is due to the rounding functionality of our software. Whenever doing a flat rate discount, you are likely going to run into 1-2c differences on your order total than what you would expect. This behaviour is because you cannot show item prices in more than 2 decimal places.