ASK HN: Vetting a Share holding agreement with an incubator

An incubator has shown interest in my startup after we met them at a startup event. When they shared their SHA (share holding agreement) with us, there were several points that alarmed me and my team. I am not sure if we're overreacting or if these are really alarming issues.

Specifically, Preferred Stocks, voting rights, tag along rights etc. How important are these and how much should an entrepreneur be willing to let go of?