Hi Krammig,
Welcome to the Samsung Developer forum!
To get started in Galaxy Store, you need to do the following:
- Sign up for a Samsung account if you don’t already have one.
- Register with Seller Portal.
- Apply for commercial seller status. Even if your app is free, all Android app publishers must have commercial seller status. The preferred way is to apply using a DUNS number. If you cannot get a DUNS number in your country, you can submit business registration documents.
- Review APK package naming and billing guidelines. Please note that .aab files are also supported.
- Register your app in Seller Portal.
- Review the App Distribution Guide, Intellectual Property Infringement Checklist, and Galaxy Self-Check List.
- Set a publication date.
You can find more information here: Get Started in Galaxy Store
In response to your questions:
a) Both APK and AAB files are supported. See https://seller.samsungapps.com/notice/getNoticeDetail.as?csNoticeID=0000008242
b) See step 4 above.