So, people tell me, will I get any link juice and serp rankings from site 4 and 5 (or even 6,7, 8...) if I link to my website like in example below?
You meant to say that if sites 4, 5, 6, etc.. is all linking to your website? If so, then yes, you will get link juice as long as your backlinks aren't set as nofollow.
Rather linking a long chain or creating a link wheel you can directly promote your website through some authentic sources.
You can't get a great deal of link juice here. Link juice will be split along this long chain. It is better to get a straight link from PR 2 site rather than this method. But above method will have a higher chance to boost your SERP rankings.
Don't do this. Interlinking all sites leave footprint. To answer your question yes, you will get link juice from site 4,5... but not nearly as much as if you link directly.
I don't know if thenavi was saying don't do what I'm suggesting, but my suggestion simply turns your proposal into a link wheel.
I was referring to linking like a chain. Link wheels are ok, but sites should be radomly interlinked.
No hard rules here but interlinking all the sites in a chain will most likely get Google's attention and the interlinked sites will be penallized/give less juice.
I do not think you will get good link juice in this case. Definitely it is good to be there, I have doubts about its effectiveness!