The median BTC fee is $3.85 currently. Using this number, then opening and closing a LN channel means that $7.70 of fees will be paid to the miners, correct?

This means that Alice and Carol would have to pay $7.70 minimally, correct?

Let’s say hypothetically that Visa or Paypal charges $1 per transaction. This means that Alice and Carol would need to do 8 or more LN transactions, otherwise it would be cheaper to use Visa or Paypal. Correct?

If Alice wants to make only one purchase at a retail store, or Alice only wants one job from Carol, then she would never use BTC, with or without LN? Correct?

It also means that they have to go through the hassle of opening a channel and deciding on when to close the channel. What happens if Alice, a day after they close the channel, that she needs a 11th project (but no more than 11) from Carol? Do they pay $7.70, or use Visa?