It has been a long time since the original question, and Power Query and the M language have continued to develop and be included in more Microsoft products (https://learn.microsoft.com/en-us/power-query/power-query-what-is-power-query). Microsoft seems to have evolved into four distinct but related offerings: (1) the M language engine; (2) Power Query desktop (in Excel, Power BI and Power BI Report Server); (3) Power Query Online, and (4) Dataflows (in Power Apps, Azure Data Factory & Fabric, and Dynamics 365).

Specifically, to provide 2024 answers your 2016 questions:

1. Microsoft seems to have settled on "Power Query M" as the 'short' name and "Power Query M formula language" as the long name (see https://learn.microsoft.com/en-us/powerquery-m/).
2. Syntax highlighting tools are still hard to find unless you use VS Code which has a useful extension (https://marketplace.visualstudio.com/items?itemName=PowerQuery.vscode-powerquery). If you use Notepad++, you can create your own user-defined language tool with the help of this tutorial and associated download files (https://ssbi-blog.de/blog/technical-topics-english/power-query-editor-using-notepad). There is also a useful online Power Query Formatter (https://www.powerqueryformatter.com/formatter).