If I get 4 domains (a.com, b.com, c.com, d.com) and each have a 301 Redirect to x.com, will building a.com, b.com, c.com, d.com links pass the SERP ranking to x.com?
It may be, but will take a time. But niche should be the same for all the domains than and than it may work.
Theoretically, yes it does, but I think having too many domains pointing to the main domain would start working against you. I am not sure if you need to waste time building links to the other sites because the engines see them as permanently moved. Why don't you just build links to the main site x.com instead of all the others? Considering most places will not allow you to put links on their site that redirect to another URL.
x.com is 3 words so I'm thinking of using "-" www.word1-word2-word3.com, better for search engines but people will type and I want to promote it as www.Word1Word2Word3.com. x.com is 18 characters and in certain situations I want to use shorter name for it which is 8 characters. Basically at most I just have 2 domains pointing to x.com.
well the pr value will pass, ranking im not too sure about. See if you are just getting links from those fours sites it kinda shows that you have a little network, where as you want to have links from various part of the net and want to be well grounded in the middle. So getting links from those four really wouldn't do much for serp. Even if you go upto 200 sites and link them to one site that wouldn;t make a different either if those 200 sites themselves are well linked and grounded
sometimes I want to use a shorten domain so its easier to remember. Longer one is more descriptive and SEO. a.com = 8 letters x.com = 16 letters