How do I efficiently change the font and the font size of my site?

Hello everyone,

I'm trying, as the title indicates, to change the font on my Drupal 7 site and/or the general size of the font. This is what I mean:

1. I would like to allow the editor of a site to switch font at will. Yes, I found the font-your-face module. On paper, this is exactly what I want. However, I couldn't get it to work properly. Fonts from "Font Squirrel" won't load and will generate an error, fonts from "Google Fonts" will be indicated as loaded (about 2700) but obviously many would be missing (passed the first page, only Serif fonts available as far as I see). Fonts found on the Google page as "Sans Serif" are found only in "Serif" version in the module. Licence Search box just returns nothing as soon as there is something typed in there.
So, I can't get it to work and there seems to have been no updates for this module in a long time. Is it working for everybody and I'm doing something terribly wrong or is there another module/best practice to achieve exactly what this module was supposed to?

2. The editor has the feeling that in general, the font is too small. While this can be fixed with some CSS lines on an ad-hoc basis, wouldn't be possible to, somehow, get all "text" to grow by x%. Meaning regardless of the actual size of the text and the actual element hosting it, all text size on the site, would simply be increased by a percentage (thus, preserving proportions). I probably ask for a lot there but that would make life so much easier than modifying font-size element by element.

Thank you for you help.