On the menu, modify #access a in your custom CSS and include whatever changes you want. On "font" stuff, you have to include the "!important" attribute otherwise you have to make font size/weight changes in several places. The !important attribute will override them in most cases.
#access a {
color: #281E01;
font-size: 110% !important;
font-weight: bold !important;
text-decoration: underline;
}
For the widget titles, I would not suggest underlining or adding bold, but just increase the size. Underlining generally indicates a link and in general widget titles are not links. Since you are using the custom fonts, again the !important attribute is required to get your custom CSS declaration to override the custom font size setting.
.widget-title {
font-size: 110% !important;
}