Cut the crap down to a minimum. Don't mix your own until you get used to the entire process. You may find that you don't want to mix your own. I know I don't. For me it is an unwanted PIA. Clean up any spills right away. Good luck.
Don't worry about the size of the neg. SOme of the most powerful contact prints I have seen were 4x5. Infact the one contact print I can't get out of my head was 2.25x2.25. Being confined to a smaller neg will force you to maximize your space and composition. It will also force you to eliminate the unneeded aspects and say only what you mean. These lessons will carry over to the larger formats where some people feel the need to pack more in. Anyone who says 4x5 is too small should probably not be trusted.