Renouncing green card as a long term resident and form 8854 and 3520

I need to renounce my green card. I have held it for 9 years, making me a long term resident. I have been living abroad for a few years with a re-entry permit. 

1. Form 8854 states that If I do not comply with all of my tax obligations in the past 5 years I can be deemed a covered expatriate, which I want to avoid. In some of the past 5 years when I was a student I did not file an income tax as I was under the <12k threshold to need to file. If the IRS sees that I did not file an income tax in some of those years will I be audited and assumed to be a covered expatriate after I file form 8854? Should I file an income tax for those years just in case? 
2.  I made a mistake on form 3520 this year. I wrote the book value instead of the fair market value for the property that I received as a gift. Can I amend it and what is the likelihood I will receive a penalty? 
3. Can I submit my I-407 ( renounce my residency) before making amendments or is it better to make the amendments before?