I485 filing when dependent is not in country

[Sam_PA1234]

Hi, 

Thanks for reading my post. 

My date might be current in next, November, Visa Bulletin for EB3, even if this is a prediction and pure speculation, I want to make sure I understand certain steps.

1. My application is in EB2, so I have to downgrade from EB2 to EB3 and file I-140 and I-485 at same time? Is this correct?
2. I am sure lawyers are busy and they make take time to apply for all these, how much time they take and I guess they have to send by end of November, is it right?
3. Do my spouse who is dependent on me, have to be in US while filing for I-485? 
4. Do I need original birth certificate for my I-485 from from my home country and specifically the city or district I was born in ? 
5. Can I get online birth certificate , will that be acceptable?

Thanks for reading my post.