I am really sorry for this noob question, but I just can't seem to find where in the options we can change the color for heading tags H1 H2 etc...

Thank you,

- Vincent

Those are changed in various areas. It could be in ATO>Style Post & Pages for the post title or in ATO>Style & edit header area for the blog title. Or you can use your own CSS in ATO>Add HTML/CSS Inserts>CSS Inserts. Sorry for not giving you a "simple" answer but Atahualpa actually makes it simpler than having to deal strictly with a CSS interface.

I'm sorry too for being dumb. I don't want my post titles in bold on single post pages. How do I make them "normal". Same size, just not bold. I assume they are "h1", but I don't see anywhere to change it.

Have you tried styling them in ATO>Style Posts & Pages>Headline Box:Text? This will affect multi post pages as well as single post pages though.