1% ivermectin is 10mg/ml, and your pour on is 5mg/ml. Just double the doseage for 1% injectible. The doseage for 1% varies on what you're using it for. I've heard 1cc per 50lbs, 1cc per 33lbs, and 1cc per 25lbs. I tend to use 1cc per 33lbs. So, your doseage would be about 1cc per 15lbs or so.
All wormers are MOST effective given orally. Pour ons are RARELY used on goats, and don't work as well as injectible or oral use.
I've used it safely in preggos, not sure if you're supposed to. A general rule is to worm before breeding season and after kidding, and avoid worming at all costs during the pregnancy. As always, it's best to do fecals to know if you have an issue, and that your drug of choice will even work.
As for withdrawl time, I don't believe there IS one known for goats. I personally don't stop drinking the milk when I use ivermectin or cydectin (though I rarely have to use it on a dairy during the milking season - I treat before breeding and right after kidding, so by the time the colostrum is done I can drink it).
A good average withdrawal time is probably 3 days to 1 week, depending on your preferences. Perhaps someone with more info might know a more 'exact' withdrawal, but most likely it will be the withdrawal known for dairy cows.