Animal Affinity as currently stated affects the base stat by 1d4+1, it does not grant an enhancement bonus so it stacks with the gloves.
This is according to the Sage, so your mileage may vary. Bruce Cordell (the guy who wrote the stuff) has specifically said he intended it to be an enhancement bonus, but Bruce Cordell isn't official, and the Sage is the closest thing to until errata is made available.
20/x3 crit range normally. 19-20 because of keen arrows ability. 18, 19, 20 should be the numbers for an improved critical character with a keen 1 number critical weapon. You are right. I doubled the 19, 20 crit range, my bad.
What gives the ability to pick out targets at 1000 ft? Well, last saturday I got a spot check of 71... 1000 ft = very roughly around 1/5 of a mile.. I don't know about you, but on some clear days I can make out a person around 1/2 a mile a way. I couldn't tell you what color their eyes were, (maybe that spot check could have), but I could tell you there was a person over there.
Besides, D&D is entertainment, it's about what you *can* do, not what you can't. We all know that the chances of an archer hitting a target at 1000 ft are slim to none, but what about a highly decorated marine with a sniper rifle? I'll bet he could handle it. So I'll bet a very well designed high power fantasy archer with all kinds of psionic/magical gear and spell could do it as well.
