Infernum rules questions

Greetings all
the questions are

1. Chain of form (pg 200), are the chosen mutations gained by the chain, limited to chains previously chosen or randomly generated?

2. Wings. Chain of wings (pg218), the mutation allows you to form wings. The first Fiend mutation gives you wings. Can a fiend hide his wings? If a fiend takes chain of wings , can he reverse it to hide his wings?

3. sorcery, gaining rituals (pg 232), the book says youget 1 ritul per skill level. is this limited to the summoning/binding/warding chains, or can the grimoire rituals be chosen. Or do the grimoire rituals even need to be chosen (pg. 236 says they are commonly known)?

all for now thanks.