Answers to your pool store recommendations:

1) No. No to "green to clean" and no to unknown ingredients in bags of shock that may raise your CYA higher if they happen to be dichlor. Better to just use bleach to shock with. No to the clarifier at this point.

2) No. Don't worry about the alk right now. Just concentrate on cleaning up the algae first and then if you want, we can help you tweak your pH and alk. But, honestly, it is ok where it is.

3) A big NO. You are right. Vinyl pools do NOT need calcium.

In a 19K gallon pool (assuming that Carl's estimate is correct), each of the 121-oz jugs of Walmart's generic 8.25% bleach will add about 4ppm of chlorine. Use that as a reference to help you determine how much bleach to add each time you test. With a CYA of 55, you'll want to shock the pool up to about 15-20ppm.

Have you ordered a Taylor K2006 kit? If so, when do you expect it to arrive?