Product Listings on Store

I'm having some issues and figured I would check with the wisdom of the crowd on this. At my company we sell large HVAC equipment and we are opening an online store that sells limited pieces of equipment.

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So here is the first issue:

1. We sell them skidded or unskidded (ready to place in or just the components that need mounting), but all our stock is unskidded. If the customer wants it skidded, we send an unskidded one over and have it skidded. Anyway long way of saying that there are two options, with two different prices, but they come from the same stock. Is there a way to have an add on option so the stock stays as one?

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The second issue is a bit more frustrating:

2. Is there a way to show the total count of inventory on the product page? I've tried code, and I know the low inventory alert exists, but we plan to keep at least 15 in stock and the message only displays when it's less than ten.