1, how long does it take IRS to approved the installmental payment on the taxes owned after filling form 9465.
2, how long will the IRS allowed to pay off.
3, what are the processes involved after turning in form 9465.

1) Normally 4-6 weeks.

2) As long as 10 years; it depends on the size of the tax debt and your ability to pay.

3) Just wait patiently; the IRS paperwork will come eventually. If 8 weeks pass, a phone call to the IRS may be in order, because, occasionally, the IRS DOES lose the paperwork.