SEO clarification questions from a newbie!

Hi there BHW!

I've been lurking around for 2 years now and 6 months back I started reading/learning about all things SEO.

I still have a couple of questions left however , it would be wonderful if someone could find the time to answer them

I have 3 completely built wordpress amazon niche sites, they are ready, made according to the rules, have keywords setup with yoast and receive a perfect rating in yoast. (kw density isnt too high or too low). All the content is hand written and very high quality.

Here go the questions:
I've read about PageRanks and Tiers, what about them ? Are Pageranks still in play in 2015 ? Do I manually build Tier 1 links or are the tiers just a myth ? Can I go ahead and fill tier 2/3 with software (dripfed, no spam)

1 of them has many articles to pull in traffic, all targeting very low competition long tail keywords. Do I create backlinks to each of these articles or to the main site ? And do I repeat the tier 1/2/3 for each of these articles ?

Thank you so much !
*extra: does someone know a good host for 4-6 WP websites ? (I read that pagespeed is important to google)

Question 1:

Pagerank was a number on a scale of 0-10 google would give websites based on how good they are in googles eyes. This is no longer updated by google.

You can manually build your tier 1 links or pay someone to do it. You tier 1 links need to be readable and unique.

Your tier 2 should be only contextual links, these articles can be unreadable but they have to be unique.

For tier 3 you use everything but again the content should be unique but does not have to be readable.

Question 2:

You should build links to each article but show a little love to the homepage too. Yes you do tier linking to each article

I use hostwinds and man they are HANDSDOWN the best hosting I have ever used. All support questions are answered in minutes, YES minutes and the speed is great.

Well, that is all the info I needed to move on Greatly appreciated, tell me how I can thank you and I will !