The programming card lets you set up those user adjustable items on the ESC that would normally require listening to a bunch of beeps to get right.

A programming card is a much easier way of doing this.

ESC's have adjustable values for

Low Voltage Cutoff ( LVC )
Motor Pulse Width
Motor Timing
Battery Type
How LVC signals you ( shut off motor completely, or merely slow it down )
etc. etc. etc

Re: BESC

I believe you mean BEC not BESC...

A BEC or Battery Eliminator Circuit, removes the need to have a separate battery pack powering the servos and electronics.

Normally the voltage from your LiPo pack is much higher than the electronics can tolerate.

A BEC is like a regulator, that takes part of the current and shunts it to heat ( on analog BEC's ) to reduce the voltage.

Some, ESC's have their own BEC's built into them.

With ESC's with BEC's the majority of these are normally Analog BECs.

Analog BECs can only handle 2 or 3 Servos when using 11.1v LiPo packs, and are useless at higher voltages.

A few, notably more expensive ESC's have SWITCHING BEC's which can handle higher input voltages and current draw ( more servos ).

Many ESC's have NO on board BEC's... referred to as "Opto" ( for optically isolated, which as far as I know they are NOT as I've never seen opto-isolator IC's on any ESC! ).

For Opto ESC's you must provide an alternative way of powering the electronics.

Remember the ESC powers the motor, not the electronics.

You can purchase a separate stand-alone BEC at minimal expense, and wire it up so that it powers the electronics.

Here is a picture of how I've wired up a BEC so that it's connector removable and can sit between the LiPo pack and the ESC...