I just moved over to the UK and I have my own student loan debt, this is what I have learned from my research.
From what I know, you are always to file US taxes for your income, regardless of if you hit the $92,000 threshold. The only difference is, you don't pay tax to the US unless you hit that amount with your earnings. Basically, the only way you stop filing US taxes is to die or renounce your citizenship.
As to your want to do income based repayments, I just set that up on my own debt this January. I'm putting a link here to the income based repayment form as a PDF so you can get an idea of what's required.
http://ifap.ed.gov/dpcletters/attachments/GEN1222AttachFINAL1845dash0102Expires20151131.pdfMy loans are held by NelNet. The person I worked with to set up my IBR payments told me it's easier to start the application process for IBR with them, rather than online on the Student loan website because I was able to set up a $0 payment with them based on my current earnings, $0 as I was unemployed and staying that way for at least 6 more months on my Fiance Visa. Rather than a payment based off my last years AGI from my taxes. So I spoke with them, they started the process and I just had to send them the form I linked. You do have to follow up every year with proof of income, I'm not sure how that will work, as 2015 will be my first renewal of it.
Hope that was helpful.
*made some typos and they were bothering me.*