If pages are not indexed make sure they are not blocked for crawling. so check your robots file. if everything is okay, submit the rest URLs manually in google search console.
PPC is Pay Per Click, its the term used to describe the type of advertising that you do with AdWords. CPC is the cost per click, it is the amount you pay for click on your ad.
here you can read the advantages and disadvantages of PPC in detail: https://www.nibusinessinfo.co.uk/content/advantages-and-disadvantages-pay-click-advertising
an outbound link is also known as an outgoing link.
if you click on a link on website A, and it takes you to the website B the link will be considered as an outbound link.