DWC heads, I need your help

I am looking at just going straight to DWC, and I think I grasp things pretty well. But I do have a few questions.

1. what is a good ph meter for DWC?
2. Same for ppm / ec meter
3. Can I use any nute line or should I stick to ones intended for hydroponic lines?
4. Containers, other tan. Having to more frquently. Would there be an advantage to s smaller shallower 3 gallon tot vs. a 5 gallon bucket?

Thanks in advance!