Regarding fees and seeing different amounts:
There have been a few reports & articles that explain this from time to time.
going off what actual agents, managers and their ilk have said in the past:
£50m will be the figure touted by Watford and what the press use as it is more sensational. It will be a true figure based on overall cost.
That cost will include agent fees, any sell-on clauses Watford will have to pay to the previous club, signing-on fees, loyalty bonuses to the player, amortised payments for the remaining fee due.
The £35m will be the figure touted by Everton and it will be the bare bones payment that we have to pay (i.e. we have to pay Watford the £5.8m per year for 6 years, regardless of anything else except if we sell him)