You are planning a Microsoft AzureAD solution for a company.

Yes – https://docs.microsoft.com/en-us/azure/active-directory-domain-services/manage-group-policySettings for user and computer objects in Azure Active Directory Domain Services (Azure AD DS) are often managed using Group Policy Objects (GPOs).

Yes – https://docs.microsoft.com/en-us/azure/active-directory-domain-services/tutorial-configure-ldapsTo communicate with your Azure Active Directory Domain Services (Azure AD DS) managed domain, the Lightweight Directory Access Protocol (LDAP) is used. By default, the LDAP traffic isn’t encrypted, which is a security concern formany environments.

Yes – https://docs.microsoft.com/en-us/azure/active-directory/azuread-dev/active-directory-authentication-librariesThe Azure Active Directory Authentication Library (ADAL) v1.0 enables application developers to authenticate users to cloud or on-premises Active Directory (AD), and obtain tokens for securing API calls.