I also hear a lot of people saying the broadcasters will have to write off the losses and won't be able to insist on the money being repaid
Highly unlikely. Remember how much money they are losing through cancelled subscriptions and plummeting ad revenues. Sky and BT have bet the farm on football driving their revenues. They will know full when that the majority of league clubs will go under anyway and will be keen on getting their money back before the bankruptcy wave starts.
I'm not so sure - if they screw football over now by bankrupting half the clubs (reclaiming or withholding money), they won't have anything to show in the longer term. I don't think it's either/or - the EPL/EFL/FA and the broadcasters will more likely come to some form of 'mutual agreement' and share the hit for this season and next (assuming they can afford to do so). Genuinely think this will lead to a resetting of things across the board though - broadcasting contracts will be renegotiated downwards, and naturally followed by transfer fees and player wages because the income won't be there to service current levels of expenditure.