I recently bought a book to help me improve my japanese but i am starting to wonder whether it was a good idea. The book i bought is this one "The complete idiot's guide - Conversational Japanese, second edition". Now i am learning from the book but it seems that everything i am learning from this book is incorrect according to my japanese friend.
An example: In the 'te'-form section the author refers to two types of verb endings; (i) and (e) [see attached image]. My friend says (and i've also read about this) that all japanese verbs end with 'u'. What is the author refering to?

Also within this book the author says that word order within a sentence (when speaking in japanese) is not important but when i showed my friend the sentences from the book she replied that although she could understand them they were 'unnatural', i am assuming she means that the sentence sounds strange to a native japanese speaker.
Who is correct, my japanese friend or this book? (Note the book is also authored by a native japanese speaker). Should i continue using the book because i don't want to learn from a source that is going to teach me an incorrect way of speaking japanese.
Another thing about the book: The title say "conversational japanese"; is there a big difference between writing japanese and speaking japanese?
An example: In the 'te'-form section the author refers to two types of verb endings; (i) and (e) [see attached image]. My friend says (and i've also read about this) that all japanese verbs end with 'u'. What is the author refering to?

Also within this book the author says that word order within a sentence (when speaking in japanese) is not important but when i showed my friend the sentences from the book she replied that although she could understand them they were 'unnatural', i am assuming she means that the sentence sounds strange to a native japanese speaker.
Who is correct, my japanese friend or this book? (Note the book is also authored by a native japanese speaker). Should i continue using the book because i don't want to learn from a source that is going to teach me an incorrect way of speaking japanese.
Another thing about the book: The title say "conversational japanese"; is there a big difference between writing japanese and speaking japanese?