I created a new Apple ID and password on my new MacAir Sonoma 14.6.1 and I wanted to keep this MacBook free of issues by not using migration, I have an iPhone and an iPad

How do I get photos, iCloud, mail etc. to work on my new Mac? I have forgotten past Apple IDs and their past passwords do I need them? Mac use to be known as user friendly, I have been using MacBook for years, it seems to be getting more complicated-am I correct in assuming this?

I set my MacBook Air up using a new Apple ID and Password. I have an iPhone and a iPad that have the same Apple IDs and Passwords but different for the new one that I set up. I was hoping not to have to use migration as this can introduce old issues to the new computer ? Is this correct?