+ 15% chlorine is hard to buy at the consumer level, outside of south Florida. It deteriorates rapidly at summer time temperatures, so IF you get it, you need to make sure it's fresh. I think there may be some places in NJ and California where it's available . . . so you may be able to find it, but that's a local question we often can't help to solve.

Keep in mind, 15% chlorine is a bit different. For example, it will start a fire if you spill it on a pile of cotton rags!

+ You definitely need a K2006 kit. Especially with a 100K gal pool, you don't want to add unnecessary chemicals. See http://pool9.net/testkits/

+ If the pool does not have really high stabilizer, the best place to start would probably be to get 1 or 2 50lb buckets of dichlor at Sams Club. They are one of the few retailers selling un-diluted dichlor, and at a really good price, too. Dichlor dissolves quickly, so it's easy to add, and it builds up your stabilizer level rapidly. Of course, if your CYA is already too high, that is not a good thing.

PoolBrand granular dichlor 50lbs @ Sams Club => ~$2.20/lb (May 2014 in Chattanooga)
PoolBrand dichlor bagged shock 24lbs @ Sams Club => ~$2.50/lb (May 2014 in Chattanooga)

Kem-Tek dichlor 22 lbs @ Amazon => ~$3.50/lb (May 2014)
Kem-Tek dichlor 12 lbs @ Amazon => ~$4.10/lb (May 2014)
Kem-Tek dichlor 5 lbs @ Amazon => ~$5.00/lb (May 2014)
Kem-Tek dichlor 2 lbs @ Amazon => ~$9.00/lb (May 2014)

Keep in mind that Amazon products normally ship free; and that in many parts of the country, you will not have to pay sales tax. Shipping + tax can increase the cost from other suppliers by 15 - 40%, so compare delivered cost, not nominal price.