Mine has both factory fitted, the front park sensors have a switch on the dash to turn them on/off. Its probably quite tricky to get that same system in your car but flush fit front parking sensor kits are available in the aftermarket which work great, look OE and work with a few wire splices. Most car manufacturers either use Cobra/Vodafone, Valeo, Xvision or Meta sensors. The Exeo has Valeo sensors from the factory but Cobra/Vodafone ones are just as good.
With regards to the heated seats question, your non heated seats won't have heated elements in them but a good trimmer/upholsterer will be able to fit them for you. It'll probably be cheaper to buy seats with them fitted though, I watch Copart salvage auctions and a few heated seat Exeos have gone through in the last week, and there's still one to go. Retrofitting the factory controls is doable, I'm pretty sure Jay1601 put a link up to the wiring diagram on his progress thread.