Capital Gains and 2/5 Rule

[Daniel Sullivan]

Hello! Looking for some help on two questions. 

Background: Considering selling my duplex. I lived in it for two of the last five years (but this will no longer be the case on July 15). Purchased for 312,000. Market value roughly 600,000. 

1. How does the 2/5 rule work exactly? Will I need to close prior to July 15 or can it be pending at that time?

2. If I am not exempt from capital gains from the 2/5 rule, how do I estimate my capital gains tax burden? I have seen tax tables and calculators online but I am still confused. Does my W2 taxable income have a role? We are married filing jointly.

Thank you!