Adding heated seats and powerable items

Hi all!

I would greatly appreciate your advice on this one: I have just ordered a 2006 Prius, and can add heated leather seats after market from Toyota. The factory does not include heated seats in any package, and I wonder now if it would draw too much electricity from the battery. Recommendations?

Also, I have a radar locator whose power is harnessed into a switchable wire on a Camry. I would like to move this to the Prius. Do any of you harness power for such accessories, and have you noticed any problems doing so wth the Prius?

Thanks much!!