I have just seen this thread. The thing I noticed was in post 4 where you mentioned having no cousins. I am exactly the same it that respect. My father had only one brother, who never married, and none of my mother's sisters had any children either, so I have no first cousins whatsoever.
When I got my Ancestry DNA results, I had some 26 000 matches, of which a little over 500 were classed as close matches. That has since risen during the past 4 years or so to 37 000, of which over 850 are considered as close matches.
I am slowly attempting to work through as many of the close matches as I can- it can be frustrating (my closest match of all has no trees at all, for example) but it has helped add a generation or two to some branches and confirm some "educated guesses."
I personally find the Thrulines option very useful, but it is important to keep in mind that, exactly as Ancestry actually say themselves, Thrulines are just a specialised form of hint, so treat them with the same caution as you would any other hint.
One piece of advice I would give is whenever possible, make a tree on Ancestry as wide as possible - the wider it is, the more chance of finding the link with 4th, 5th etc cousins. Note that tree does not need to be the one linked to the DNA results, nor does it have to be public (though it does need to be a searchable tree I think). A while back I came across a marriage on Ancestry, checked it on Scotland's People, and subsequently added the husband and four daughters to my private, research tree (ie not my public DNA linked one). Two days later, a DNA match appeared on Thrulines through one of the daughters, and I was able to confirm the connection via Scotland's People and by messaging my match. (The fact that everyone on both lines was born, married and died in Scotland helped of course.)