If / When - When is it possible to use either?

What often puzzles non-native speakers are the sentences when either if or when is possible (= you can use either).

Are there any general rules that explain when either is fine?

Sorry for the weird examples.

1)

a. When / If I'm ill, I lie in bed.

Is there any, however subtle, difference in meaning between if and when in this sentence?
I think that both when and if can be replaced with "every time" here:

Every time I'm ill, I lie in bed.

Another example that I think falls into this "category":

b. Many people don't care when / if they see a woman breastfeeding her baby in a public place such as a park.

2) What if we are describing character traits and habits:

a. When / if you like to cause harm, you are evil.
b. When / if you drink alcohol to excess habitually, you are an alcoholic.

In a., when sounds odd to me. In b., both look OK to me.

3) What about:

Many people don't care when / if a woman breastfeeds her baby in a public place such as a park.

Thanks in advance, as always.

EDIT: Made the examples more accesible.