This ofcourse will depend on where have you applied. Typically, places where there are more influx of immigrants, hence more applicants, takes more time. Places like New York, LA, Dallas are running anywhere from a year to 18 months. If you are in places like Nebraska it could be as soon as six months. Answer to your first question, you have to be Permanent resident for at least 5 yrs to be eligible for naturalization. The exception to this rule is that, if you have applied for PR through marriage to US citizen and you are still married to same person, than you are eligible for naturalization after 3 yrs. If you are applying in 5 yrs category, you are eligible to apply 90 days prior to your 5th anniversary of your Permanent Residency. I hope this has been helpful to you.