AppQoS (Application Quality of Service) is a Junos OS feature that provides advanced control and prioritization of application traffic. With AppQoS, you can classify application traffic, assign a forwarding class to the traffic, and apply quality of service (QoS) policies to the traffic. You can also re-write DSCP values and reserve bandwidth for important applications. However, AppQoS does not re-write the TTL or rate-limit traffic.
Source: Juniper Networks, Security, Specialist (JNCIS-SEC) Study Guide. Chapter 3: AppSecure. Page 66-67.

A single vSRX or cSRX cannot provide both firewall and NAT services simultaneously. To meet the minimum requirements for this deployment, you need to deploy a vSRX for firewall services and a separate vSRX for NAT services (option B), or a cSRX for firewall services and a separate cSRX for NAT services (option C). This is according to the Juniper Networks Certified Security Specialist (JNCIS-SEC) Study Guide.

A single vSRX or cSRX cannot provide both firewall and NAT services simultaneously. To meet the minimum requirements for this deployment, you need to deploy a vSRX for firewall services and a separate vSRX for NAT services (option B), or a cSRX for firewall services and a separate cSRX for NAT services (option C).