What is the exact effect that affection has on companions?

I know that in general, a higher affection score raises the chance for a successful crew skill check and reduces the time to completion, but what I'm looking for here is hard numbers so I can decide whether or not buying a bunch of gifts to raise my companion's affection is worth it to me?

What I'm particularly interested in is the following at each affection level (0, 2000, 4000, 6000, 8000, and 10000):

• % reductions in skill time
• Bonus to skill crit rate

If there are any effects other than that, I'd love to hear about those too! This obviously can be difficult, particularly calculating the crit rate, since it would require a lot of data points. But if you can find external research on it or can convince your guild to help you out with data points (much like some seemed to do with calculating average values for various crew skill missions), that'd be awesome!

As a rough rule of thumb, every 750 affection is worth roughly a 1% reduction in completion time on crew skill tasks.

Edit: Comments indicate that the first 450 points of companion affection are worth 2% off the top, and that further affection follows the 1%/750 formula. I haven't seen the exact data set, but this does fit the patterns I've seen closely enough to be plausible.