painting house siding: general questions

[Stuart Wier]

1. If wood house siding starts out in good or new condition,
when is it time to repaint?

2. If the paint has a condition ranging from solid,
to hairline cracks along the grain, to cracks both
ways, to paint flaking off:
a. how much old paint do you remove? can you leave the
paint with a few hairline cracks and paint over that
part?
b. how do you remove the cracked or flaking old paint
over a large area?

3. any recommendations for primer and top coat paint?

4. anything else I've overlooked?

I live in a climate which is sunny and dry most of the time.

Stu Wier