after sending the eBook in, can i resend it again if i find something that needs to be changed?
I want to make sure everything is spaced out okay
Yes. On ebooks if you want to revise it or need to correct something just click on the revise link on the book's link in My Projects. Then go through the wizard. When you get to the part where the documents are uploaded, delete the old one and upload the new, just follow the wizard to the end and click save and publish. It will take about 2 to 4 weeks on average for the changes to make to Amazon etc. Easy to do. I do it all the time.