MRH is a great magazine as is MRH Running Extra - June 2019. Lots of additional model railroad stuff also available on TrainMaster TV. On the other hand (or side of the Atlantic) I also spend a lot of time on the MERG (Model Electronic Railway Group) site (.uk) and Forum.

there's also an excellent JMRI email group:

https://groups.io/g/jmriusers

and the website, of course(which I expect you already know about),

http://jmri.org/

Great places to ask questions, get technical info about the guts of JMRI, and feel the "pulse" of this excellent, organic group-developed and supported application.

Blair

.....around late Aug/Early Sept each year,They allow access to the "Beta test" versions year round.

Waiting for the "Production version" gives you the best stable program to work with

The ESU files are evolving all the time as ESU decoders evolve,as they do not follow the NMRA CV

 setup per the standards.

IT does help to keep the Java Software updated as well, check at http://getjava.com 

Does help to have access to IE 10  Browser when checking/updating Java

all other Browsers no longer use Java/Java script

JMRI production versions are released twice a year just before the NMRA national convention and just before Christmas. JMRI version 4.16 should be released within the next couple of weeks. Development versions release about every 3 weeks. If you are comfortable with computers, don't hesitate to use a development version as they are more stable then most people think. Unreleased alpha versions are also available to those that wish.

Java and Java script are 2 different things. You don't need a browser that supports java script to download and install Java.