Help!!! My OBC Showing THIS:(

[Taj]

Gentlemen,

So I visited Autozone and here are the codes:

Troubleshooting: P1115

Definition:
HO2S sensor heater circuit short to ground bank 1
Sensor 1
Explanation:
Open or short circuit condition
Probable cause:
Failed HO2S11 (Heated Oxygen sensor- Bank 1 sensor).

The other code is P0455
This is a correct. The top cover of the fuel cap magnetic lock is not functioning. It doesn't lock. I bought a new fuel cap with a key that locks the cap to secure the gas tank.

What do I do now?

Also some questions:

1. Which code reader/engine scanner/Diagnostic Tool is the best? Autozone used an Actron.
2. Can I actually disconnect the battery while I work in Boxster? There is information that I can disconnect only for 20 secs.

Please help.

Thanks.