The UK is facing the payment of around 100 billion pounds to the EU before leaving it. Would that money be returned if the UK reapplies and joins the EU later?
The "divorce bill" effectively represents a one-time payment for the UK's existing liabilities (pensions, payments previously agreed but not yet paid) and a share of the structural costs involved in the withdrawal (e.g. the cost of moving UK based EU institutions elsewhere). Some of these costs may be cancelled against the value of the assets and credits that the EU owes the UK in return but, rather like a divorce between people, the intent is to end up with "separate finances".
Since the money is actually paying for things, it is unlikely that it would be returned if the UK rejoined (if you remarry your ex-wife you can't claim a rebate from the removal firm that took her stuff away). But equally it is unlikely that the UK would then be asked to double-pay for any costs the divorce bill is intended to cover.
I do not think so. It's not just money that was going to sit around. That money is to fund projects that the UK has committed to like the Galloper Wind Farm in Suffolk, England.
There is some punitive tendency in the EU bureaucracy, to make a divorce as expensive as possible, and to make the way back in really hard, too. So, apart from actual costs coming with Brexit, which can't be refunded anyway, there is little intention to give a rebate to a renegade country.