A) 7lbs of dichlor should get you right up to 30.

1) Does it matter? CYA will affect measured TA consistently. You will raise it if your pH is unstable - you will determine the best level. The CYA component factors out when comparing new TA reading to old, why bother doing the calculation?
2) A little, maybe 10ppm salt in a jug of bleach.
3) Just fine - no differrent than any other source of chlorine.