The .011 strings all came unwound at the ball end after installation. Anyone else have this issue?

From my years of selling D'addario strings, this is a very rare problem as opposed to other brands where it is a regular occurrence. Go to their website and I'm sure they will be happy to replace the defective strings.

Why did the single string go from 69 cents or over $4?

You are comparing apples and oranges. A string might be $.69 but what was the shipping charge? You have to look at the total price which is why people who only buy items with "free shipping" often pay more than they should. To put a single string in a box (for protection) and ship it the postage is almost $3.00. Do a search for PL010 and you will find various "multi-packs" available. First Stop Music Shop custom packages both 5 and 10 packs of this string.

Are the strings individually wrapped?

No, they are in a single poly bag inside the cardboard packet.

Why are the .0135 $8? They are literally $.99 on Daddario's website. The ones being sold by amazon

Re-enter your search criteria. I paid $0.89 for individual ones and $3.99 for a pack of 5. From Amaxon. Must be a typo or mis-labeling you found on a page.