Key features and updates in Java SE 11 include:

1. LTS Release: Java SE 11 is an LTS (Long Term Support) release, meaning that Oracle provides updates for a longer period compared to non-LTS releases.

2. Removal of Java EE and CORBA Modules: As part of the ongoing project to make the Java SE platform more flexible and scalable, a number of modules were removed, including Java EE and CORBA modules.

3. HTTP Client API: A new HTTP Client API that supports HTTP/2 and WebSocket was introduced. This new API is a replacement for the legacy HttpURLConnection API and provides more efficient ways to communicate over the network.

4. Java Flight Recorder: This feature was open-sourced in Java 11. It’s a tool for collecting diagnostic and profiling data about a running Java application.

5. Epsilon: A No-Op Garbage Collector: This is a new experimental garbage collector that handles memory allocation but does not implement any actual memory reclamation mechanism. It can be useful for performance testing and certain types of applications where garbage collection isn’t needed.

6. Local-Variable Syntax for Lambda Parameters: Java SE 11 allows var to be used when declaring the formal parameters of implicitly typed lambda expressions.

7. Dynamic Class-File Constants: This feature extends the Java class-file format to support a new constant-pool form, CONSTANT_Dynamic. The goal of this is to reduce the cost and disruption of creating new forms of materializable class-file constants and also offers broader options for expressivity and performance.

8. New Methods in String class: Several useful new methods were added to java.lang.String, including isBlank(), lines(), strip(), repeat(), and stripLeading() / stripTrailing().