The low emission zone (Umweltzone) covers the areas inside the middle ring road (B2R, Mittlerer Ring) only.
http://www.muenchen.de/rathaus/home_..._emission_zone

See map:
http://www.muenchen.de/rathaus/Stadt...mweltzone.html

When you book a hotel outside the ring road (e.g. Arabellapark Sheraton/Westin, many in the North, like Olympic Park), you do not need a sticker.

When you need to look for P+R, there is plently. Maybe you can pick an area convenient to you (where are you coming from, where do you go after Munich?). Larger P+Rs: East: Riem, Messe, Daglfing, Arabellapark (free parking on the main road, Englschalkinger Straße) (all direct to main station); North: Fröttmanning (see post above); South: Ottobrunn area, Perlach (all direct to main station).