Nice to hear! :)
There is no good reason for limiting it to 1024 honestly. Nobody said something, and i didn't thought about it either. Some effects and especially effect chains can be quite heavy, but who am i to limit it based on my low specs. On the other hand. The transformation will usually lead to having less available pixels anyway, so its not much different from upscaling afterwards i guess. In the next version (dropping within the next 3 weeks) you will be able to export up to 4096x4096, so basically unlimited i would say, as well as rectangular textures as was wished in the comment before.
On the UI: What lines do you mean? The marking lines on the canvas - The width can be edited in in the top left options. If you mean the separation between the containers/canvases, that i can easily change. Or do you mean the font sizes in general?