There is a warranty on the
There is a warranty on the battery-pack and electric portion of the drivetrain. It varies based on state, but is either 8-yr/100k miles, or 10-yr/150k miles. If you are within that timeframe/mileage and your battery fails, it is fully covered under warranty for a replacement.
Nobody knows what the replacement battery cost will be 8 years down the line. For the people replacing hybrid batteries right now (for vehicles several years old right now), there are more expensive OEM options, as well as after-market companies that are selling battery packs for much cheaper than Honda or Toyota want directly. Right now, the OEM cost of the battery pack is likely higher than that $1500 estimate, but it's impossible to say whether that is still accurate forecasting that many years in the future.
The regen occurs under normal slowing, but it recovers more energy if you engage the brakes while slowing. There is a real-time display on the left side of the dash that shows how much /. how fast the car is recovering energy. While coasting in normal mode, it typically shows 2 bars of regen. While coast in B mode (which ramps up the regen), it typically shows 4 bars of regen, and doesn't coast as far. When braking even at moderate rates, it can max out the recovery to all bars (I think it's 10 or 12). The trick to maximizing range is to not use such hard braking that all of it can't be recovered, and needs to engage the friction brakes rather than the regen portion. You want as much deceleration as possible to be used to generate electrical energy instead.