Your account must meet one of the following to enable traffic analytics:
Your account must have any one of the following Azure roles at the subscription scope: owner, contributor, reader, or network contributor.
Reference:
https://docs.microsoft.com/en-us/azure/network-watcher/traffic-analytics-faq

Explanation:
Box 1: 6
5 latest daily recovery points, which includes the weekly backup from the previous Sunday, plus the monthly recovery point.
8th January = 5 daily backups (1 weekly backup included) + 1 Monthly = 6 backups Box 2: 8
5 latest daily recovery points, plus two weekly backups, plus the monthly recovery point.
5 daily backups (11th Sunday weekly backup included) + 1 weekly backup (4th Sunday) + 1 Monthly + 1 Yearly = 8 backups

Explanation:
Box 1: Yes
A Basic Load Balancer supports virtual machines in a single availability set or virtual machine scale set.
Box 2: Yes
When using load-balancing rules with Azure Load Balancer, you need to specify health probes to allow Load Balancer to detect the backend endpoint status. The configuration of the health probe and probe responses determine which backend pool instances will receive new flows. You can use health probes to detect the failure of an application on a backend endpoint. You can also generate a custom response to a health probe and use the health probe for flow control to manage load or planned downtime. When a health probe fails, Load Balancer will stop sending new flows to the respective unhealthy instance. Outbound connectivity is not impacted, only inbound connectivity is impacted.
Box 3: No
There will be no loadbalancing between the VMs.
Basic Load Balancer: Virtual machines in a single availability set or virtual machine scale set.
Standard Load Balancer: Any virtual machines or virtual machine scale sets in a single virtual network.
Reference:
https://docs.microsoft.com/en-us/azure/load-balancer/skus
https://docs.microsoft.com/en-us/azure/load-balancer/load-balancer-custom-probe-overview

A Log Analytics workspace - Traffic Analytics requires a Log Analytics workspace to store and analyze network traffic data.
A Data Collection Rule (DCR) in Azure Monitor - You need to create a Data Collection Rule within Azure Monitor to specify what data should be collected and sent to the Log Analytics workspace, including the network traffic data for Traffic Analytics.