1. Temperature is important throughout the life of your beer, even after you get it in bottles. You want to make sure your beer is never exposed to temps over 70-75 degrees or it will skunk.
2. In terms of readings it may boost your OG, SG, and FG readings but it should not affect your attenuation (which is what matters). What I mean is, your SG may be higher than it would be for a 5 gallon batch, but your OG would have been high too so your total attenuation should be the same either way. One thing you might want to do is cut back on your priming sugar so as not to overcarb.
And now we go AG!
On Tap: Nadda
Planning: Extra Special Bitter