hi Klaus,
I personally follow J2EE Patterns - but mainly because I'm a Java Developer. Usually I end up with a **** load of .js files, and sometimes because I do not really have access to a node instance this is not "super" because it impacts a bit the number of requests - nothing that a concat task cannot solve.
One instance application I would usually end up with Singletons, just for easy access - but case the application could retain multiple objects then an instance member.
Older UI5 versions you can require at top and use it inside your class, newer versions of UI5 you require on the define and utilize on extend.. and a class is instantiated by a "new", I'm not too sure what you meant with that.
I usually don't use OData Model unless I need direct OData functionality like pagination - JSONModel all the way - and I store most of the model data on the Core singleton just so the next developer don't find it too weird, but it's not good design (however is sort of the SAP way).
Eclipse vs Sublime? - Well.. when I code on own laptop / desktop I use Eclipse, because my hardware is a beast.. on work laptop I use Sublime because i5 is basically shyt and on the current customer I'm using Orion (what you call Web IDE) - basically because the machine is too slow for Eclipse, they won't provide me a Sublime license and the only think I can really use that is decent is Chrome.
Cheers,
Dan.