Logic gates in a schematic
What is the most common schematic to show a logic-and gate (without the symbol itself)? 




Figure 1. Function Block Diagram (FBD) is popular in some PLC programming languages, with Germans particularly fond of it. Image source: Science Direct.


  I have come across various schematics showing input nodes A and B (with nothing connected to it), but I'm not sure how those would be shown in a schematic to simulate the on/off states of those inputs. 


I think we'd need an example from you.


  Additionally, how does one usually show that a logic gate's output is either in the On or Off position, ...




Figure 2. Siemens LOGO! program status monitoring. (Click for full-scale view.) Image source: Treffpunkt Eltern.

In this example logic status is indicated by colour.