This post is very link heavy because I intend it to be a reference page for me.
One of the great things about the internet is that education can be a marketing tool, and that is just fine by me! People add value to their products by giving away expertise. A company that has many useful "threads" is Superior Threads, they have everything from cheat sheets and trouble shooting, to really terrible jokes (which are clearly rubbing off on me). Also, great thread and good thread charts. If you buy thread online then get a thread chart. Computer monitors are not the best color matching tools, especially for variegated threads.
So here are links to reference tools specific to the HQ Sweet Sixteen:
Great basic chart on thread tension
Longarm needle guide
Longarm machine thread reference guide
This page allows you to cross reference what you find in the needle guide and the thread reference guide, so you can see which # needle to get for which thread
Brilliant trouble shooting flowchart
Videos by Dr. Bob
Type "Thread therapy with Dr. Bob" into Youtube, to find some informative stuff there too. I like that Superior is not just trying to sell you thread, they also want you to have a good time using it.
I really like Isacord too, but if you use it you are on your own. No information, no jokes! Sewforless has good deals, especially at Thanksgiving. For solid Isacord colors in humungous spools this is an amazing deal.
Thus endeth the links...