Yes. Once the battery is charged, you can leave the maintainer connected to the battery to keep the battery in a charged state, so it will be ready when you are.  You only need to unplug the unit from the wall before starting your vehicle.

You would need to connect the  ring terminal to the bolt that comes out of the connector on your battery, not the battery post itself.

The charger has safety features built in.  If the charger can not detect that it is connected to a battery, then it will not send a charge through the cables.  Your battery must have at least 3 volts in order to be able to be charged.

The charger has safety features built in.  If the charger can not detect that it is connected to a battery, then it will not send a charge through the cables.  

No, but the higher the Ah the battery is, the longer it will take to charge the battery.

There is a protective sticker on the LCD screen; Please make sure it has been removed.

The charger reconditions the battery as it charges.  It can take up to 24 hours to fully charge the battery.  Once the battery is fully charged, the bar will no longer flash.

The bars on the LCD screen will be solid, instead of flashing.

Auto shops test your battery for current under load. It will only show if the car will start.  If your battery is old or has not been kept charged it is possible that it is weakening.