Question about DB

Hello folks! I will be traveling to germany in two weeks (mostly by train), and got some question on the tickets I've bought:

• I will be arriving by frankfurt airport, and I bought a ticket that goes from Frankfurt Airport -> Frankfurt Hbf, and them Frankfurt Hbf -> Hamburg. Is there a big chance that my first train will be delayed? I understand that it will be coming from another city, and it may arive late on the airport, making me miss my connection. Is it better to just take a local train to the frankfurt Hbf?
• For this trip, I received a email saying 'Fahrplanänderung: Bitte Reiseplan prüfen'. When I look into the app, it says 'Timetable change. Please select an alternative connection'. But its not clear for me what I should do, or what of my two trains is changed. Do I need to do anything? It seems i cannot do anything via app