You're saying that it's my using four widgets that's reduced the sizes of the images [...]. So now I'll remove the 2nd, 3rd and 4th and see if the original is legible.

That's not at all what I said (and I didn't mention the "single full-width footer column" either). I said that the default width of each footer area you used is roughly 1/4 of the main column width - period: removing the widgets from areas 2,3,4 won't change the width of area 1 by itself. And I said you can change the widths via CSS editing but we can't tell you how do to it if you don't tell us exactly what you want (that is, if you don't tell us how many side-by-side images you want in the footer area, and if you don't tell us where the first one should start and where the last one should end).

Another thing to note: A forum thread isn't a sort of personal communication on any issue you might think of. A forum thread is supposed to be of use to others too, so it should be confined to what its title says: for a different problem you start a new thread.

@mrstringer2012:
a) Yes, that's what I'm telling you. So yes, the stuff in the CSS editor may eventually become long.

But keep in mind that when you apply the same change to different elements, you combine the respective commands into one. For example, if you want a white bg to both the footer widget area and the credit area, you won't write this:

#colophon {
    background-color: #fff;
}
#copyright {
    background-color: #fff;
}

you'll write this:

#colophon, #copyright {
	background-color: #fff;
}

b) Chateau has four footer widget areas, designed to show up side-by-side below the main column; so the width of each widget area is 1/4 of the main column width (I'm simplifying - actually it's less, because of the margins). Your question can't be answered before you decide how exactly you want to change that: Three widget areas side-by-side in place of four? Four widget areas in two rows of two? Four widget areas side-by-side but spanning the width of main column plus sidebar? Widget areas of unequal width? Other? And don't forget that a) you don't have to use all four areas, b) each area accepts as many widgets as you like.

.wf-active .sidebar-widget h1 {
    font-size: 1em;
}
#colophon {
    background-color: #fff;
}

Is that what you tried?

.post-entry {
    font-size:120%;
}

b) I'm not sure my definition of "body" is your definition of "body". Body means all the content. Are you talking about that or are you talking about the main column only?

c) To change the background color of the footer area in Chateau, you add this:

#colophon {
    background-color:#456789;
}

(456789 is just an example: you change it to the hex code for the color you prefer.)

.wf-active .sidebar-widget h1 {font-size: 1em;}

Ems are very sensitive, so if you want something larger, you should try 1.1em or 1.2em before you go to 2em.