Hi friends, need your help! Your experience will help me a lot

I have started an amazon kdp recently like most people here. I'm doing clring books, puzzle books, fr now and published 4 books till now. I started by aug 1

As per my understanding i want to run ads on my books SP and get reviews frm ARC at start

Is still method is correct? Need your thoughts about this

I planned to spend some money on ads

Also, please tell me about kindle ebook I'm not aware of that