The correct choices for settings to configure when FortiGate is being deployed as a root FortiGate in a Security Fabric topology are:
B. FortiAnalyzer IP address - This setting is required to send logs and reports to the FortiAnalyzer for analysis and storage.
D. Fabric name - This setting is essential to identify the Security Fabric and differentiate it from other fabrics in the network.

The correct answer is: C. Both control ECMP algorithms.
In the context of SD-WAN (Software-Defined Wide Area Network), ECMP (Equal-Cost Multi-Path) algorithms are used to determine the path packets should take through the network. Both IPv4 and SD- WAN ECMP algorithms control how traffic is load-balanced across multiple paths to a destination. While IPv4 ECMP operates at the network layer (Layer 3) of the OSI model, SD-WAN ECMP operates at a higher level, typically involving application-aware routing and more advanced traffic steering capabilities.

The certificate warning errors occur because the SSL inspection profile is configured to use a private CA certificate that is not recognized by the browser as being signed by a trusted CA. For the browser to trust the FortiGate's re-signed certificates, the CA certificate used by FortiGate for SSL inspection must be installed in the browser's trusted certificate store. Until the browser recognizes the certificate authority (CA) as trusted, it will continue to display warning errors when accessing HTTPS websites.
References:
* FortiOS 7.4.1 Administration Guide: SSL/SSH Inspection Configuration

FortiGate supports both pre-shared key and certificate signature methods for IKEv1 authentication. These methods provide flexibility depending on the security requirements of the network. Additionally, FortiGate supports Extended Authentication (XAuth), which requests a username and password from the remote peer, enhancing security by adding an extra layer of authentication. The XAuth method does not necessarily make the authentication faster; it is an additional security measure.
References:
* FortiOS 7.4.1 Administration Guide: IPsec VPN Configuration