A sizing chart can be found here:
Yes, of course. There is no way I would hand wash a t-shirt. They should be washing inside-out with cold water and no bleach. They can be tumble dried on low heat, but some may prefer to line dry them to minimize shrinkage.
Though there isn't an easy way to do that, if you select the higher priced one and add on the price of the other reward you would like, there will be a place to note both rewards on the survey.
After the funding period is over and payments clear, you will receive a notification to fill out a survey. That survey is where you will specify size, color, style, mailing address, etc.
Don't see the answer to your question? Ask the project creator directly.