So I'm thinking that I'm on the home straight. I have a mobi file that works properly having tested it on my specifically-purchased-for-testing Kindle Fire (even though they're not on sale in the UK yet).
I upload my file and:
1) The file I get back for checking from Amazon has no extension and will not display on the Previewer. So I manually add in a 'mobi' extension, however I'm concerned that I should have to do this as I'm [i]supposed[/i] to be looking for problems.
2) I uploaded a substantially larger cover file to KDP, which when viewed in the Previewer and on my Fire has now replaced the html version that I created (as per the children's book example) and I have a section of a much larger image slapped at the front of my book. This is wrong, but is uploading a file to the same (much smaller) size as my html cover really the solution?
3) Finally, the mobi file is about 1Mb more than the epub that I started out with. I read somewhere that the KF8 process bundles in legacy files, however I had hoped that these would be stripped out before publishing (?)
I will of course now go looking for answers, but thought that I should ask the community ...have I missed something?
1) This may be the issue of your web browser. At least Firefox and Internet Explorer should give you the proper extension (.mobi) when you download the processed file from the "enhanced previewer."
2) Amazon forces the uploaded cover/product image inside every mobi file. You can remove the html cover from your mobi file and upload a JPEG image 600x800 pixels to KDP. This will work fine as a full-screen cover on the vast majority of Kindles (3:4 aspect ratio of the screen), but you will have margins at the top and bottom of the cover on the Fire. If you want a full-screen cover on the Fire, you can try an image 600 x 960 pixels. Also keep in mind that KDP will reduce quality of your uploaded cover to about 60KB, there is no way around it.
3) KindleGen 2.4 adds your source files to the .mobi file. After you upload the mobi file to KDP, you should have a stripped-down version of the file in the "enhanced previewer". You can also try programs KindleStrip and Mobi Unpack, which you can find on the mobileread forum (a more complicated option). My experience shows that the "enhanced previewer" will remove the source files only if your overblown mobi file is bigger than 3 megabytes, otherwise KDP will keep the source files in your ebook.
man2010: Thanks for your detailed response. Here's what I did.
1) I tried both IE & Firefox, but both had the same problem. To get round this basically I just added a .mobi extension. Not ideal, however I plan to check this isn't a problem when it's listed on the store.
2) I removed the html cover (why on earth does the Amazon example file show this?) and corresponding references and then made a new epub. I made another front cover 1000 pixels tall and 853 pixels wide. This is proportionately half the portrait height of the Fire and therefore the right proportion for a fixed layout landscape cover.
3) I had a look at KindleStripper and didn't like the idea of losing data that might be required at a later stage ...so I did not use it (thankfully).
My .mobi file worked as intended on my Fire. I proceeded with my upload. the KDP system subsequently reduced the size of my file (without any need for KindleStripper). I'm now waiting for it to appear on the Amazon store. As soon as it does, I'll purchase a copy and ensure that everything works as it should.