1) You ask 50$ annual fee. I am sure you are aware that according to MyFxBook terms any indicator or EA which uses their data needs to be free.
2) The same EA is available on several online forums. Though, I am not sure if you borrowed the code or somebody borrowed it from you.
1) I'm not aware of this, please provide link. Also, as soon as data used are over coded with personal idea, I wouldn't consider this as Myfxbook rights anymore. Regarding indicator from Forex 21, it provides exactly data as Myfxbook not mine EA/Indicator. Only Basic package uses as Myfxbook.
2) As far as I know, I'm one of the first to propose that kind of strategy. I have myself been inspired from FXCM that proposes this strategy since 3 or 4 years at least. But the way I use it is a bit different.