When do I use the bass roll off switch? When I am close to a subject? Also, is the base roll off notch that part of the little graphic on the microphone that looks like a line that suddenly bends down on an angle?

God I must sound like a moron!

1. You don't sound like a moron.
2. Yes, the little "slope" line that is angled up and then flat is the bass rolloff.
3. Use it in rumbling environments or windy environments. Sometimes you just gotta experiment while monitoring to decide when you do and don't need it.

So the rolloff helps when it is windy, but what do you lose when you use it outside? I shoot sporting events and it is often windy and there is always crowd noice that I don't always want to capture.

Indoors, might you use it at recitals, etc?

I just bought an AT897 and don't have much time to experiment before I need to use it for some indoor events. I'll also be using it outdoors in the spring.

Thanks in advance!

The bass roll-off switch on the K6 has a very high knee point, starting to roll off just above 500 hz.
In contrast, the bass roll-off on the AT897 starts at 80 hz.
The K6 switch is really intended for use in extreme conditions, and I think this decision was also influenced by the mic having such a hot output, which can already easily overload a normal mic input even without a lot of bass energy present.
So listen carefully when you apply the K6 switch, to make sure you aren't loosing too much bass. Also be careful that you aren't overloading your mic input when using the K6/ME66, regardless of where you have the switch.
The AT897 will almost certainly sound smoother indoors and shouldn't give you any overloading problems unless you're in an extremely loud event or your mic input is extremely sensitive.