Need info for changing Grand Company individually and as an FC

I have some questions regarding changing grand company.

1) As an individual, if you change your grand company, then go back to the original one, do you retain your rank? Ex. Now I am a 2nd Storm Lt. in Maelstrom. If I switch to Adders, then back to Maelstrom at a later date, am I still a 2nd Storm Lt.?

2) If a free company is rank 5 and has all perks unlocked, then changes it's grand company affiliation, does the rank and perks get reset back to rank 1?

Answers are super helpful if you got em!!!!!