I'd also not deduct a point from every forecast. [I found that a pain when I tried to update scores over holiday period and made mistakes because of it]
If by that you're referring to not including the "stake" in the returns (i.e. in the tipping comp, a winning pick at a price of 2.5 gives you a return of 1.5pts, not 2.5), then I'd agree, you'd be right to include the stake in the FA Cup comp.In the FA Cup comp, you're staking part of your bank each round on your selection, whereas in the weekly tipping comp, you're effectively "given" five free 1-point picks each week, but you're not actually risking any of your bank (so your score can't go down, only up). So the return you get is only the winnings from your selection, you don't get the stake back as you never really staked anything to begin with.