font size; site tagline; losing formatting

Hello, Thanks for the theme and for your good support. Three different questions: (1) Is there a way I can change the default text font across the whole site, in a way that easily withstands future theme updates? (2) Is there a way I can increase size of site tagline text, (and hopefully italicize it as well), in a way that easily withstands future theme updates? Unrelated to above: (3) I don't know why this is, but sometimes when I'm in edit-mode of my homepage, all the spacing-formatting (returns) disappears from the content text, and I have to go back to an earlier revision in order to retrieve the spacing-formatting. Naturally it is both annoying and troublesome and means potential lost changes. This seems to (illogically) correlate to when I make changes in other areas of the edit page (last instance of this was changing where sidebar is). (May or may not be relevant: when this just happened again, when I was in revisions mode searching for an earlier version of the page to revert to, some (or perhaps all) OTHER of my site's pages were not pulling up, giving an "Error establishing a database connection" message.) -- How do I get the spacing-formatting (returns) to stay-put in my homepage when I'm editing other-than-content options on the edit page? Thank you.