Reference:
https://docs.microsoft.com/en-us/azure/virtual-machines/workloads/sap/deployment-guide

Explanation

Box 1: No
You can't use an Azure Basic Load Balancer to create failover cluster solutions based on Windows Server Failover Clustering or Linux Pacemaker. Instead, you need to use the Azure Standard Load Balancer SKU.
Box 2: Yes
Azure Availability Zones is one of the high-availability features that Azure provides. Using Availability Zones improves the overall availability of SAP workloads on Azure.
The SAP application layer is deployed across one Azure availability set. For high availability of SAP Central Services, you can deploy two VMs in a separate availability set.
Box 3: Yes
You must use Azure Managed Disks when you deploy to Azure Availability Zones.
Reference:
https://docs.microsoft.com/en-us/azure/virtual-machines/workloads/sap/sap-ha-availability-zones
https://docs.microsoft.com/en-us/azure/virtual-machines/workloads/sap/sap-proximity-placement-scenarios#com
https://docs.microsoft.com/en-us/azure/architecture/reference-architectures/sap/sap-netweaver

Explanation:
Box 1: true
enableAcceleratedNetworking: If the network interface is accelerated networking enabled.
To further reduce network latency between Azure VMs, we [Micorosoft] recommend that you choose Azure Accelerated Networking. Use it when you deploy Azure VMs for an SAP workload, especially for the SAP application layer and the SAP DBMS layer.
Box 2: true
Write Accelerator should be used for the volumes that contain the transaction log or redo logs of a DBMS. It is not recommended to use Write Accelerator for the data volumes of a DBMS as the feature has been optimized to be used against log disks.
Reference:
https://docs.microsoft.com/en-us/azure/virtual-machines/workloads/sap/dbms_guide_general

https://help.sap.com/viewer/f2ad7797884249eeb2e91dc26a991196/3.0.3.0/en-US

Backup architecture
* The backup process begins by creating a Recovery services vault in Azure. This vault will be used to store the backups and recovery points created over time.
* The Azure VM running SAP HANA server is registered with the vault, and the databases to be backed-up are discovered. To enable the Azure Backup service to discover databases, a preregistration script must be run on the HANA server as a root user.
* This script creates AZUREWLBACKUPHANAUSER DB user and a corresponding key with the same name in hdbuserstore. Refer to the setting up permissions section to understand more about what the script does.
* Azure Backup Service now installs the Azure Backup Plugin for HANA on the registered SAP HANA server.
* The AZUREWLBACKUPHANAUSER DB user created by the preregistration script is used by the Azure Backup Plugin for HANA to perform all backup and restore operations. If you attempt to configure backup for SAP HANA DBs without running this script, you might receive the following error: UserErrorHanaScriptNotRun.
* To configure backup on the databases that are discovered, choose the required backup policy and enable backups.
* Once the backup is configured, Azure Backup service sets up the Backint parameters at the DATABASE level on the protected SAP HANA server.
* The Azure Backup Plugin for HANA maintains all the backup schedules and policy details. It triggers the scheduled backups and communicates with the HANA Backup Engine through the Backint APIs.
* The HANA Backup Engine returns a Backint stream with the data to be backed up.
* All the scheduled backups and on-demand backups (triggered from the Azure portal) that are either full or differential are initiated by the Azure Backup Plugin for HANA. However, log backups are managed and triggered by HANA Backup Engineitself.
References:
https://docs.microsoft.com/en-us/azure/backup/sap-hana-db-about
https://docs.microsoft.com/en-us/azure/backup/backup-azure-sap-hana-database#configure-backup