Most ( not all admittedly) loans end once the last game of the season has been played in May. Players at their end of their contracts on 30/6 still are paid by the parent club for a short period . The 1/8 date is irrelevant in payment terms
Sanchos fee may due to be paid in September 25 under the original transfer but I am pretty sure any final payment has to be advanced if a permanent transfer from Utd as well as all outstanding sums due to him when/ if a permanent transfer takes place. The amortised balance will be reflected in the subsequent accounts . In terms of availability of cash to Man Utd to pay BD it depends on the fee arrangement between Utd & Chelsea
There is no set dates when instalments have to be met that’s a matter between the clubs save they have to be settled within the length of the contract. Yes amortisation is set against contract length although FFP/PSR now has restrictions. I don’t know if you have seen any confirmation yet but as the standard accounting procedure and FFP in this regard aren’t aligned accounts may well need to be viewed differently
One transfer windows in September one in January but a club can buy a player at any time they just can’t register them. With regard to fees payable to agents it’s far from as clear cut as you suggest it would be worth your while looking at the clubs annual submission of fees paid to agents/ intermediaries
See attached and scroll down to Utds for example
https://www.thefa.com/-/media/thefa...24/football-agent-transactions-2023-2024.ashx