hi,
I'm far from being a weather radar artist, since I fly weather radar equipped aircrafts only from a few months
For point 1, I think that it is not so conservative... yellow stuff is not really the most funny situation, while red can get you into serious troubles. Have you ever tried to get in between two nice red cells ? It happened to me a couple of times, and it's not so relaxing
When avoiding you also have to consider downwind and upwind conditions. There might be some huge Cb's that can still shake you in a good way in 25 nm range while downwind.
If I'm flying in a 80 nm Map Range, a select the tilt to have echoes on top of my screen, the classic green band that is caused by terrain returns. In 160 nm map range, I do more or less the same.
Anyway, waiting for some usefull replies to your question as well
Ciao