Doing some research before my first season. Was wondering what everyone's opinion on tubing is. I do not know how many taps I will have yet, but estimating 25 tapes per line (no main line) gravity fed or thinking about the shurflo pump. Some short steep slope, some long gradual slope.

1) 5/16 or 3/16?
2) Brand of tubing?
3) Best place to purchase?
4) check valve taps or not?

Thanks in advance for taking the time to answer.