Not exactly a fan of “place text object here but type the text somewhere else”, I prefer in-place editing.
And yes, the selection of the different text objects can be challenging when you have more than just a few, either you have to find it doubleclicking on each of, dozens?, hundreds? of elements in the Object list, all called “Text” (it will be great if you can assign a name to each, besides the “Text” descriptor, the first few words of the text will be fine by default), or you have to use the Pick Objects (hand icon) tool, wich is challenging in itself because of the need to click exactly inside the shape of the lines that form a letter, you could be clicking in the hole inside an “O” and nothing happens.
By the way, what is the actual state of WonderBrush V3, is there somewhere a binary to try?
Premade objects can be as easy as putting a bunch of objects in a folder and some menu or toolbox as a convenience to access them easily.
The infinite canvas, I guess that’s more complicated, though I hope not infinitely complicated 
I always liked the concept of a universal canvas/document format that remains open and you switch to different tools (from little utilities to whole programs) depending on what part you need to work on. It was already tried with OpenDoc in the nineties, but I guess it was too much against vendor lock-in and beautiful closed gardens for Steve Jobs taste.
But I digress, althoug nice, this is not necessary and will complicate things a lot.