What if I live in US for few years while on FLR(m) in UK

Dear,

I have been in UK since 2009, I recently got my UK passport.

My wife came in UK in Jan 2015 on PBS dependent, but as I got my ILR on long term residence, she changed her status to FLR(m), we are having and extension after one year for her FLR(m). But due to family situation I have to move to USA on an investor Visa and my wife will be joining me to USA. We also have 2 year old baby who has UK passport.

My questions are,

1) If we move to USA then what will happen to her FLR(M) status?
2) How long can she live outside UK on FLR(m)?
3) What if her FLR(m) expires and how to renew?
4) How long can, me the UK passport holder and my daughter with UK passport can stay outside UK for?
5)If FlR(m) expired then how can my wife enter UK again?
6) She has worked in uk since 2015 on NI, if she leaves uk does she has to apply all again?
7) What will be the best option you will suggest on this?

Many thanks