Hi -For a manual, you can use either a serif typeface (such as Times Roman) or a sans serif typeface (such as Arial). If you're using an HTML compiler, or a help file creator, use a standard typeface - since the face will have to be on the user's computer. If you're using PDF, be sure to embed the type files into the pdf file.
For an electronic manual, you'd use a slightly larger typeface than you would for print- 12-15 pt size and slightly wider leading between lines (at least 2 pts larger than the typeface)
Headings will normally run anywhere from 16-24 pts, and are generally bold or a contrasting typeface. Same for title sizes - you're just going to have to look at it in context to your body copy and see what looks best.
There are some free screen capture programs athttp://www.nonags.com/nonagsbut I use a shareware program called SnagIt. (http://www.snagit.com) - it does a good job of letting you annotate and crop screenshots.
Hope that helps!
