Brita Filters are distillation filters if I'm not mistaken. RO is reverse osmosis filtration, and DI is distilled filtration. RO is good, DI is alright, but RO/DI is GREAT. You can buy RO/DI from your LFS, or a water supply store. Whatever you buy, make sure it is RO/DI filtered, if it doesn't say so, ask someone.
Buy a different test kit. Testing parameters for saltwater and freshwater is completely different. In no way should you trust a cheap product, especially one that says it will work for either type of aquarium system.
You need a test kit that tests for:
pH
Ammonia
Nitrites
Nitrates
Testing for Carbon Dioxide is not something that is necessary in this hobby unless you get into Calcium and Alk issues.
Your pH is higher than desireable. You want between 8.0-8.3.
SG stands for Specific Gravity (Salinity) which is measured with a hydrometer or refractometer. Refractometers are one of the best test tools you can buy, they are very accurate and start at reasonable prices.
Ammonia Detox is a product that de-toxifies ammonia in aquarium water. It is good for emergencies, but using it during your cycle will only cause more grief.