Issues with how ebay calculates shipping (multiple quantity order of same item, etc)

[ucl7632]

I have been having some issues with how ebay calculates and charges buyers for shipping, which have required out of pocket spending to deliver items. Hoping for some tips, thanks in advance. 

My current Shipping Policy =

• Shipping Method = 'standard' (No items need special handling)
• Cost Type = 'calculated' (so it accounts for buyers location).
• I have not included any handling cost

Questions/Issues:

1. Multiple quantity purchase of the same item:
   1. Ebay charges the buyer assuming I can fit an infinite quantity of this item into the package dimensions for one and just multiplies the package weight by the quantity ordered. 
      1. I recently disabled 'combined payments & shipping' thinking this would resolve the issue, but I don't think it has. This issue has resulted in underpayment for shipping from buyers for multiple orders.
2. Item's over $750 require signature confirmation to keep seller protection:
   1. Is there a way to add this fee as a shipping cost if purchase price meets this requirement?
3. Liability coverage for items > $100:
   1. Most shipping services provide $100 liability coverage and the option to add coverage up to the item cost for a fee. Is there a way to factor into calculated shipping charged to the buyer, so this added liability coverage can be charged.
4. For all above questions, since I use calculated shipping, might have multiple quantity of an item or accept an offer I haven't thought using the handling fee would address these under charging cases (as all vary based on each buyer). 

Thank you for any guidance or advice you might have to share. 

[lady_madonna]

@ucl7632 

When you use calculated shipping, are you entering the exact precise dimensions & weight of the prepackaged item?

https://www.ebay.com/help/selling/posting-items/postage-rates/shipping-calculator?id=4178

Do you have your shipping details to account for shipping multiple items? Such as X amount for each additional item based on weight?

[ucl7632]

@lady_madonna thanks for your reply.

For some items that are already packaged in shippable boxes I use those dimensions and weight for calculated shipping (for other items I input box size & total weight needed to ship quantity = 1 of the item). 

I do not have multiple item shipping detail added. I did not see a feature allowing me to input an weight dependent factor, only a fixed dollar add on. Since shipping cost changes based on where it is going, weight & package dimensions a fixed dollar amount seemed difficult to determine.