1. Elasticsearch is an open source search and analytics engine that can run in a distributed environment. It provides RESTful APIs to ingest and retrieve high volume, velocity data. Elasticsearch is used for log analytics, full-text search, and so on.
2. Apache Freemarker is a popular template engine that can generate text output based on template and variable data. Apache Freemarker templates use a custom programming language named Freemarker Template Language (FTL), which is used to write programming constructs in presentation views.

3. A Flux that can be used to send 0..N number of data and a Mono that can be used to send 0..1 data.
4. A Blog Management System is a system that must be publicly accessible via the internet and registered users must be able to write, edit, and delete content. There must be capabilities for administrators to curate the Blog Management System.
5. A Controller Advice is used to hold @ExceptionHandler, @InitBinder, or @ModelAttribute methods, which are meant to be shared across multiple @Controller classes.
6. A Password Encoder is used to secure a password using a one-way hashing algorithm (SHA-256, MD5, BCrypt, and more) for storing so that it cannot be reversed to find the original password.
7. This can be done by returning a UserDetailsRepositoryReactiveAuthenticationManager as a bean, which is configured to have a ReactiveUserDetailsService implementation and a PasswordEncoder implementation.