Hi, fellow blue 505 user!
You have good color sense!
As to converting and all the other stuff , as you roam the rooms you will pick up good tips and pointers.
I'm the other way, I like big font sizes but in calibre you should be able to make them big or small going down to 1 font size. On side of Convert EBOOKS icon (arrow) is batch settings and you can set it up the way you like it and experiment with it. You can make it as small as you like or as large as you like.
Another option after you get used to your reader is doing font hacks, which are easy , and you can pick a small and thin type if you want to put more on page. Again I hacked it and put on BIG and Bold!
You can batch convert 100 or 200 at a time , now if they are big ebooks yeah it will take a while, but not bad. This site has lots of them for free download.
epub and lrf are both great formats. Since I did put hacked font on it, I am using more lrf lately. They both are good. And there are lots of options on batch convert, about how you want page set up and other features. Trial and error.