I was thinking of setting up fastlane to submit my app instead of submitting it manually, which is time-consuming. Would that mean I have to redo everything from scratch i.e. provisioning profile, certs and app name/ description (found in metadata) as that info is already set up in App Store? Would switching over cause any issues?
https://docs.fastlane.tools/getting-started/ios/setup/ Is a good introduction to get started. If your app is already on the store Fastlane will get all the metadata, screenshots, identifier etc.
With regards to certificates and provisioning profiles you can either choose to set everything up "completely new" with match or use your existing ones with cert and sigh
Later option really depends on how many people/apps are involved.