For the conversions the first thing you will need is the eBook Publisher from eti available here
http://www.ebooktechnologies.com/sup...r_download.htm
That will allow you to create imp format books. Once you have that you can start adding things like to mobi2imp, see the stickies in this forum for that one. It will let you convert mobi format to imp with a pretty good success rate. I just did all of the Honor Harrington books from Baen with it.
Also Calibre has tools that you can use things like mobi2oeb that will let you handle mobi files that mobi2imp might fail on. It will get you the html that can be used by eBook Publisher to create an imp file. I don't think Calibre can handle that directly but there were some posts about adding that into Calibre. You could also try Geb Librarian
https://wiki.mobileread.com/wiki/GEB_Librarian
I've never used that one but a lot of people do.
Getting your books onto the ebw-1150 I would say use the impserve program created by ashkulz you can find it in the stickies of this forum as well. It works well letting you browse your books on your pc and load them to the reader. You can also use the smart media card with a card reader you get your imp books onto the reader without any need for extra software. Geb Librarian will also handle contecting your reader and pc.
I usually purchase books from fictionwise they have them in the correct format but I usually get either the lit or mobi version of the book that I want. Baen also has them in rb format but again I usually get those in html format and convert them unless I'm in a hurry then I'll download the mobi version of the books that I've purchased and do a quick conversion with mobi2imp.