Could you tell me if there is any difference in meaning between what happens when/if... and what will happen when/if... For example:
What happens if you lose your job? Do you have a plan?
What will happen if you lose your job? Do you have a plan?
We tend to use the present tense when we talk about universal situations.
What happens when you drop a lighted match into a can of petrol?
What happens if/when you mix oil and water?
We use the future more when talking about a particular situation.
What will happen if we don't arrive at the airport in good time?
What will happen if our application for a visa is refused?
In many contexts, including your examples, both are possible.