I'm not wanting to change my ibooks over to another format but I'd rather have access to my ebooks and my ibooks on my PC and Kindle. Is there an iBooks App for this? Can I just put them in my iCloud and access them that way?
No. On every purchase page in the iBookstore it has a Requirements section which tells you that an iOS device is needed to read the book.
Nonetheless some books, those in .epub format and without DRM may be readable on a PC or Kindle. Many free books and those from certain publishers like O'Reillly do not have DRM. For apps, do a google search on "how read epub on PC" etc.