Should be nothing harder than a simple css change in the theme. Unfortunately I don't know what features CAF provide in that regard (whether it's a fixed theme you cannot change, or whether you can customise it).
Edit: For the admins, there is a "Style Manager" in the Administration Centre. If you go in there, you can't edit the default style directly but you can create a new one.
For the quotes, if you do that, then find this section:
blockquote.bbc_alternate_quote,
blockquote.bbc_standard_quote {
padding: 15px 10px;
border-style: solid;
border-width: 0 0 3px;
border-color: #b5c4cc;
background-color: #e0eef6;
color: #768094;
}
The "color" value is the text colour, in hex, but you can also use css colour names too,
All about CSS Color Codes, includes color picker and hex color chart.
If you add a "font-size" item, you can also change the font size.
color: black;
font-size: small;
Then just need to "Pick" the style back on the style manager page. If you make a mistake just delete the new style and it should revert to the default.