On another note, one really neat feature would be to allow the creation of additional global field properties and property data types so that we can get more columns added to the entity fields grid. That would make it so much easier and faster to see and edit our field level custom properties instead of having to click each field and then looking at the lower custom properties name/value grid.
No, as they're not intended to be that. If you want new properties in the generated code, simply add a custom partial class: the 'dsl' to type the property is C# or vb.net in that case, which is suitable for that purpose.