Most restaurants claim that they use 2 oz. of dressing per salad, at least the ones that provide their nutritional information. As far as the salad shaker goes, I personally just use a tupperware container with a tight lid. It doesn't matter what it is, so long as it closes tight and has enough room for the salad to move around in.
As far as fats, you do need a certain amount in your diet in order for your skin to not get horribly dry and for your hair to not be brittle. It sounds like you have the right idea as far as fat is going. Just remember that things like cheese do have a small amount of saturated fat in them usually. Other than that, as long as it's healthy fats and you're not lacking in other departments or feeling hungry, then I say stick with what works, unless a doctor tells you otherwise.
Oh, and I almost forgot. There are several companies that make travel sized versions of salad dressings for people who want a healthy option when eating out. One of them is
Girard's. If you click on packettes, they have a few healthier options. Another company is
Minimus. If you click on food, and then lite dressings, you'll find a few dressings from Kraft, Ken's, Hidden Valley, and the Newman's Own Light Italian. Of course, the other option is to get a very small container, pour in some measured dressing, and take it with you. That really only works if you're going to be going to dinner fairly soon and anticipate eating a salad, though.
Good luck!