You are practiacally dead on, but here's the detailed look:
14.64:1, (but who's counting [

]) is used for ALL closed loop functions unless there is an event (cat overtemp, etc). This is because all emissions are lowest at stoich. If you go lean (to improve mileage), your CO and HC's are absolute lowest, but NOx (Oxides of Nitrogen - a key SMOG element) go through the freakin' roof. I'm sure, that if our cats could remove it, we would already be running much leaner. Since we are running at stoich, I have to assume that we are incapable of running in a "lean-burn" mode. More research is needed.
Closed Loop: Engine temps at "operating" levels, cats warm and ECU uses the first o2 sensor in the stream to compare to the command table (1.0 lambda is stoich). The O2 reading is constantly fedback to the ECU and fuel trims are adjusted to keep the engine at stoich. There is CONSTANT fluctuation, so the readings will swap from .995-1.005 (ish), so the reading has some "hysteresis" (roughly speaking, a feedback lag). This lean/rich/lean helps keep the errors down.
Open Loop: Regardless of temp/cats, the engine is kept at a specific fuel ratio from the command table (.860 lambda or about 12.44:1) that is
read by the O2's (they just don't have a say in the output). The A/F ratio is determined by the MAF voltage, IAT readings (to determine the MASS of air moving) and fuel lookup tables that decide what pulse width to use on your injectors. This mode is used for warm up and max power. Now, the O2 sensor readings
do go BACK to the tables for correction. So, if you change your MAF and the O2's sense a change in open loop, your long term fuel trims will actually make changes, just much later in the process, and they are AVERAGED corrections.