I'll answer these backwards:
3. The "Install Themes" tab is right next to the "Manage Themes" tab (that is, you need to be on the "Themes" page in order to see the two little tabs in the top left of the page). Here's a screenshot I took for reference: http://i.imgur.com/GW9rI.png
2. To be honest, most theme frameworks (if you want to call them that, since many of them are really just advanced parent themes) require some knowledge of css and php, with the exception of perhaps Genesis because it has a bunch of ready-to-go child themes already made (Genesis costs a lot of money though). I think there are some other frameworks that allow you to edit/change stuff from extensive option panels, but I can't name any off the top of my head.
1. Child themes might seem complicated if you are first starting, but they are the only recommended way of making changes to your parent them (e.g. Thematic). This is because the child theme preserves changes when the parent theme gets updated (as opposed to losing the changes you make to the parent theme when it gets updated). The parent theme is essentially the building block for your child theme. Child themes are not only seen with "frameworks" such as Thematic, but should be used with any parent theme, such as Twenty Eleven or Twenty Ten.
So in short, you are indeed looking to use a child theme regardless of what parent theme or "framework" you might choose. Unfortunately Thematic has not been updated in some time, so it hasn't drawn too many developers. Hopefully some renewed activity can change that though. I hope to help people out by creating a bunch of brand new child themes with options panels soon, but in the mean time there are some existing, albeit outdated and unsupported, child themes http://themeshaper.com/category/thematic-child-themes/ out there.
I'd personally recommend thematic if you want to learn more about how themes work and get your hands dirty. Otherwise I'd look at something like Genesis for ready-to-go themes.