I dont know what the purple spray is either but you might want to get some tea tree oil from boots and put 5 drops in a litre of water and spray thier legs and feet , it works magic on killing lice and is only about 3 quid for a bottle that will last for ages , NOTE! do NOT apply neat to anything, it is very powerful and MUST be diluted!
Check the birds for clean smooth scales on thier legs! if raised and lumpy dont buy them . Clean bright eyes and no runny tears too.
I think you got it covered other than being prepared for them stealing your heart and making you laff with so many daft things they do, if you eat in the garden in good weather (ha ha ) lay a place for them , I have given up trying to eat without them nicking a bit of my bacon sarnies!!
Good luck and enjoy them , oh you will I garantee it !! give it a week and you'll want more ! ;D