I am now on LTBV and two years passed. My business growing slower than I expected in business plan but it growing and all the time I have positive income. I hope that I passed the good way: established from zero business for online sales goods for craft/scrapbooking with $100K/year income that goes 99% from overseas. I think immigration officers love new export business :-)
Now I am thinking that approaching time to final step - convert LTBV to permanent residency.

Does anyone know how much time take this step? First application take me 4 month, first conversion (after 9 month) take one day and one letter and how much time I need to wait for final conversion?
Does anyone know - is this conversion need any additional payment? I cannot find any info on official site and worrying.
And last but not least: is there any hidden "stones under the water"? Does officers carp your work and carefully inspect all aspect of your business? Or maybe this is a easiest step and I'm worried for nothing.

Thank you.