Yes, layers would help for quick edits. Take note of the options for hiding and/or locking layers. Sometimes they can be as annoying as helpful, but once you get the hang of it.....well, and find your own personal workflow, you can deal with it.
Will you have a different template for each size of button? Or do you plan to make them all at the same size, and scale them just before printing?
If you're going to have several templates, you can make custom templates in Inkscape! I'm in a bit of a hurry, but there's a tutorial, if I can find it.... Ahh, here:
http://libregraphicsworld.org/blog/entry/using-templates-in-inkscape It is slightly old, but I don't think any of the template related features have changed much, if at all.
If you don't need more than 1 template, well, even so, it still could be helpful to make a custom template.
Basically you can make the template to have any option that's available in Inkscape. If you want a grid, configure a grid. Guides too. If you want the same background, let's say like a pattern print or a giant daisy on every single button, put it in the template. Certain text that might be on all of them, yes, and even layers, that too. Oh, just re-reading your message, you said you're going to make a sheet of these. So you can make a template for that too, if you want. I'd have to give it some thought, exactly how. But I know it can be done.
There's an extension for printing marks, if you need them. I think it's packed with Inkscape. But if you don't find it, try here:
http://wiki.inkscape.org/wiki/index.php/Inkscape_ExtensionsI can't speak much to keeping the background nice, with the high resolution, because resolution confuses me. But as long as you import the high resolution images, use the proper import options, and don't scale them, you should be fine. But there may be other issues. Lazur can probably explain that. If he doesn't reply, please post a new reply (in this thread) with only that question in it, and I'll try to grab his attention.
Just out of curiosity, how do you handle the roundness of the button? I mean, how to you apply the printed design without making creases or folds, to allow for the convex profile?