Sorry completly wrong place to post but, I do need some answers if anyone knows!!!

I just reduced a male 2yr old (sib.) husky as of 3days ago he was extremely skinny ribs and spine you can see and feel.

Questions are ;

1. How much should I be feeding him?

2. He now has the runs everytime he poops as I am feeling him about 3 cups a day 3x a day is that to much?

3. Will his runs stop after gaining weight?

4. Is the food I am feeding him making him gets the runs?

Also everytime he eats he downs it in 30seconds should I buy a slow feeder or will this stop after he knows he can trust I will never not feed him and he will always get food in his new home? Anyways thank you!

Add he most likely doesn't have worms as he was chained to a pole without food for the most of his time at his last "home" but who knows I will be calling vet just wanted to make sure in the mean time I could be doing something different or if I am doing everything right