#1 Yes. There is a slight bit of regeneration anytime you take your foot off the gas, if the battery is low, and you are traveling at a decent speed. Experienced drivers have found ways to eliminate this resistance when NOT desired, such as coasting down a long hill. Neutral will eliminate resistance is most cases ( but surprisingly, not all! ) and so will depressing the accelerator pedal a slight bit, but not enough to accelerate... like a 2mm depress.

#2 In stop & go or slow & go conditions, most, but not all of the recharging will come from regenerative braking. In real life, you tend to need more power than regenerative brakes can put back in.

Sadly, short commutes, those less than 5 miles are poor on gas mileage from a cold start. The engine / catalyst needs to be at full temperatures, and the battery at a high state of charge for the real hybrid advantage to kick in. This normally occurs AFTER 3 miles or more.

On a hot day, on the way home, you could get 2 out of 3 miles on battery alone.
I suspect all 3 miles will use gas on the way there on a cold engine.