1.5 batch in 6.5 gallon bucket effects

I did a stove top 1.5 gallon batch of AG using the filter bag technique (See http://brewing.lustreking.com/articles/stovetopallgrain.html) Don't really want to head this thread in that direction, more important to my question is the volume I stuck into my 6.5 gallon bucket.

I had a starting OG of 1.056. My software gave me a 7gm pitch of dry yeast. I hydrated it for 15 min at 100-degree water and dumped in. I have at 70 degree and got pretty good fermentation in 6 hour, is has been about 30 hours now and the gas production has slowed a ton, there is a nice layer of foam. Is this normal? I have had longer gas production on my other 5 gallon batches in this fermenter.

Is the 1.5 in the larger bucket making the gas production less evident with the large volume of gas vs liquid?

I also looked and saw that I really only needed to us 4 grams of yeast, did the almost double pitch of yeast increase this speed to the fast ferment?

Thought i should have just said "put" not "stuck"...I don't think I have a "stuck" fermentation, bad choice of words

You definitely over pitched. Don't worry though, your beer is fine. Just treat it like normal.