I can help you out.
First, what colors are you going to make? If you are making darker colors, watermelon, blacks, green pumpkins, you won't need stabilizer. If you are using light colors or any purples, you will need some (maybe 15 drops for your 2 cups).
On softener, it depends on what plastic you are starting with. FYI, 5 parts plastic to 1 part salt is not very much salt.
The standard senko recipe is:
1 cup plastic (regular)
1/2 cup salt (popcorn salt works great or any really small grain)
1/4 cup softener
The first time you make sticks with this formula, you will swear that it will never get pourable as it is very thick until it gets to a good temperature. If you add the salt to already heated plastic, you will have to heat it again before using it as it will drop the temperature.
Tim