Hi CS L,
1. You may also need a foreign supplementary page - SA105.
Link here to SA105: Self Assessment: UK property (SA105)
2. No you cannot file the informtion separately, it must all be done online or all on paper.
3 Yes that is the correct address.
4. Yes paper returns needs to be filed by 31/10/22 for the 21/22 tax year.
5. Once you have submitted the return you can check to see if it has been logged as received , allow 10 days from date of posting.
Contact details here:
Self Assessment: general enquiries