You can start negotiations with players that have under 6 months left on their contract for european based players, not including UK. You can only start negotiations with UK based players when they have less than 1 month left on their contract.
So Ings could not have signed for an English team until very recently. However he could have signed with european teams, excluding UK teams, from January.
If the payer is under 24, a compensation fee is neccessary to protect the 'selling' club from losing young (accademy) players for nothing. If the buying club, Liverpool, can't agree a compensation fee with the selling club, Burnley, then a tribunal settles the compensation fee. Liverpool must either agree a fee with Burnley before the tribunal, or pay the compensation fee that the tribunal settles on.