I have two questions, too, so I should be on topic, right?
1) For most of my books, I just open them up and read them and everything's fine with a default font size of 2 (of 8). I now have about 4 or 5 books with font sizes that range from too small to MUCH MUCH too small. Setting the font size up to 5 (of 8) changes it to bearable, but still a little small. How do I go about changing the font size so I can go back to my lazy way of just reading? I tried converting from AZW3 to AZW3 while changing the Base Font from the default of 0.0 up to 14.0, but with no effect.
2) When I first started using calibre, I took the lazy way out and just typed "a:B0084AXZRI" into the ID field. Then, at some point an upgrade started filling in the full data, so it comes in as "mobi-asin:B0084AXZRI" instead. Is there a way to replace all instances of "a:" with "mobi-asin:"? It looks to me like these strings are recognized as Identifier types, instead of data stored in the field.

I'd really hate to have to go in and edit 184+ records just cause I did something stoopid.
Thanks for reading.