Personaly, I recomend Photoelectric for any dwelling unit setting.
Most fires in this enviroment will start by smoldering.
Ionization is more for a rapid heat type fire ( this is why they go off with steam, outside of a bathroom door etc).
I also recomend a co detector, where fossil fuels are burned. Reno, Not sure about the claim for temps, but any electronic device will have issues in the extreme.
Any life safety device should be replaced after ten (10) years.
Photos do require some maintanence, Vacuum once a year. The LED is very atractive to spiders and such in the cooler seasons, This will most definately cause "INADVERTANT" alarms. ( In this end of the trade... We don't call them "false", the detector did it's job.
It just had an outside influence!
Your wireing/install plan sounds fine.
As stated Heats in the garage (attached) and co detectors.
Co is close to the weight of o2, so placement should be close to the smokes placement.
Standard smokes will cover 900sq ft. (15' radious from center). However the radiant rise of the smoke from a fire would dictate that the smoke be 3' from a doorway and no closer than 1 ft from the wall/corner (2' Is best).
http://chemistry.about.com/cs/howthingswork/a/aa071401a.htm
