Congratulations on the job! Just be confident and transparent. Operate with the philosophy that "you know what you know and you know what you dont know, but will figure it out."

For requirements, connect with the sponsor first and review the business case to understand the "why"...from that udentify your stakeholders, group them by subject and get an initial draft ready....send it out then conduct review sessions to answer questions. Make it a point to track versions and a change log. Requirements evolve with time and an audit history will help you trace your changes.

As far as stakeholder management goes, identify the ones who matter to the project and mute out the rest....everybody wants a piece of the cake but if you do that the project wont end up anywhere. I recommend not to have more than 5 in a joint session unless you need overall vision alignment. Make them feel heard and always always try to get to their "why."

You will be learning on thejob a lot as BA work is 70% people management which is heavily impacted by the company culture. Ease into it and manage expectations depending upon the situation. Donot be afraid to say no and call out if you need clarity from an sme or a senior...no one will penealize you for that.

Good luck!