Okay i was wondering if i Transferred say 35m to my friends account then my friend traded it to my Second account which is then on a VPN and then traded to a gold buyer. Could my main be banned for it?

No

i've only bought gold and i've never had an account banned for it. 

Not really

Id love all feedback related to this topic thanks.

I've bought and sold gold through one account for awhile and haven't been banned yet. You'll be fine.

If i sold gold, To a trusted GoldBuyer. Would Paypal or Bank Transfer be safer?

you wont get banned as long you don't talk during the trade. but since is the same IP that is going around yeah u wont get banned since jagex can see u are just xfering.

If i was about to sell 1.5B why would Bank transfer be safer than using Paypal/Skrill?

Trade over 5b+ and never get banned.. never 1 time , only banned for botting  but not for rwt

Highly unlikely to be banned for that. I have sold billions of gp and never been banned

Jagex won't care at all over 35M, and even if you do large amounts if you're smart about it you won't receive bans generally. You'll be completely fine, or should be.