Concurrently pending H1B application renewal and Employer based green card. Also family-based green card application?

[KapilJ]

I am working on H1B status from last 3 years and my h1b renewal is in progress by the same company. Also My company filed the green card and I-485 has been approved. 
My Wife is a US citizen. 
My question is: 
1) After our marriage, my spouse can concurrently file the green card application for me. Are the H1B and these two green card applications (one through my employer and other one through family) mutually exclusive or unnecessary redundancy? 
2) Does the pending H1B have any unintended effect on the validity of our marriage-based green card application? 
3) Can my employer withdraw the H1B petition and green card application, so I can start work as soon as I have my EAD? 
Thank you!