OE is Output Enable. :-)
Logic ICs with the same number have the same functionality and pinout across manufacturers. A 74xx32 is always a quad 2-input OR gate. The technology used may be different though; a 74LS32 is low-power Schottky, while a 74HC32 is high speed CMOS. These families have their particular properties, which you'll find in a "Logic Family Guide".
Sometimes there are small differences in the details. I remember a Schmitt-Trigger inverter I once use for an oscillator, which generated a complete different frequency when using make Y instead of X. Reason: different trigger levels, these are not standardized.
I never realized this before, but you're right: the datasheets have many terms and abbreviations which are not clearly explained. At least not in the datasheet. The datasheet often refers to the Logic Family Guide, which contains information concerning the whole series. That way they avoid datasheets becoming twice as long because they contain all this information time and again.
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I checked with a few datasheets from different manufacturers, and I must say, it might have been worse. For many parameters there are tables with a column "symbol", and next to it a column "parameter", which describes it briefly. The "OE" appears as abbreviation in truth tables, but for what it stands for you'll have to read the ICs description.
See also this answer about datasheets.
The Source and Bulk do not have to be connected.
In power devices, and especially in discrete transistors, the S & B are built very close together and shorted. This improves the breakdown voltage performance of the transistor.
In an IC, in some CMOS processes, the B of NMOS devices is always substrate (ground), and so in structures such as NOR gates which have 2 NMOS in series, the 2nd NMOS doesn't have the S=B.
Generally performance (gm, current) is better with S=B, but some technologies don't allow the B to be separated from the substrate for NMOS devices. PMOS devices in an IC generally can have separate S & B connections.
If you connected the B of PMOS to GND, you would have a parasitic diode from S to B (GND), and so your supply would be shorted (unless you wanted to run on a very low supply voltage of << 0.6 V). Some very low voltage circuits do use this technique.
A MOSFET connected as a diode will generally have worse performance than a PN junction in terms of the 'sharpness' of the curve. However, FETs with low threshold voltage (say 0.4 V or lower) will turn on at a lower voltage than a diode will, and this can be useful in low voltage circuits. For the same reason that the B is always substrate in some CMOS ICs, there isn't the flexibility to use a PN junction as a diode in all circuit configurations. If the PN junction of a PMOS is used (P = Source, N = Bulk), then there are some additional parasitics that need to be considered that make this not useful generally.
Best Answer
"Bypass" in radio circuits generally refers to a decoupling circuit, usually a low impedance capacitor to ground, to allow the high frequency signals to "bypass" the rest of the circuit. It could be a local power supply for an amplifier, or a reference point where you don't want stray RF signals. Or a measure of the signal strength, fed back into the RF stages, to control their gain (AGC) in which case you don't even want audio noise on it - hence the massive C17.
And in this circuit you can see pin 1 is connected to GND via C2, pin 7 via C7, and pin 16 via C16 and C17. The next page of the circuit lists all of these as "bypass" capacitors.
As Peter's answer suggests, some of them may have an auxiliary function : for example, with the waveband switch set to "FM", the "RF Bypass" pin is shorted to ground, which can reasonably be assumed to kill the RF amplifier.
As Pin 2 is the "FM IF input" we can assume the RF and mixer stages for FM are handled by a separate circuit, not this RF stage. (When these chips were made, IC processes were limited in frequency range : they couldn't handle 100MHz signals very well) - in fact the circuits on pages 6 and 8 confirm that.