Greetings Earthlings!

1) Plugged in immediately so fully charged whenever next use happens to be. Will unplug if I notice it is fully charged.
2) Venting seems to be the same as other Prii. Just use front/rear defroster with the blower
3) Keep in the high 30's...Never noticed much difference in mileage when inflating higher and felt the ride was worse. Just not worth it.
4) I recommend keeping it on EV always. You might use gas for a mile or two at the end (or not) and would therefore need to visit the gas station every 300 commutes (less than once a year) and pay that extra $20 to make sure your fuel doesn't go stale. Let the car drive and just enjoy it.
5) DRLs will consume some energy but as the other note clearly stated, it's unlikely you would notice the difference. The loss of a great safety feature for what at the end of a year would likely be less than $1 in electricity is a poor choice.

For #5, I assumed 30W (25 times what Skylis measured in the other thread) for 1 hour (assumes you averaged 28MPH on your 28 mile commute) for 5 days a week for 52 weeks a year -> 7.8KWh which at $0.12/KWh -> $0.94...Keep the radio off and you might save another dollar or two each year.