OBEL stands for On-Board Effects Loop. It is a wiring design inside the guitar which uses a separate 1/4" stereo jack to allow the direct output from the pickups to go to effects pedals and then back into the guitar for post-effects volume control. The purpose of the OBEL is to allow for volume adjustments on the guitar after being processed by effects. You may notice that distortion and envelope filters respond differently with volume adjustments on a standard electric guitar. Using an OBEL allows for consistent response from your effects pedals/processors at any guitar volume.
We recommend to use a junction box with a stereo 1/4" guitar cable to connect the guitar to a junction box (a stereo Y-cable can be used instead). A junction box looks like an effects pedal. It has a 1/4" stereo input jack on one side, which is where the stereo guitar cable from the guitar's OBEL jack plugs into. The other side of the junction box has 2 mono 1/4" jacks. One of those jacks is a send to the input of your effects the other is a return from the output of your effects. Using one mono guitar fx patch cable, connect the send from the junction box into the input of your first effect pedal, and the the return from the junction box plugs into the output of your last effects pedal in the chain.
Yes, you do not have to use the OBEL in order to plug in your guitar to your effects. You can simply bypass the OBEL using the OBEL bypass mini-toggle switch on the guitar and use the guitar as a standard electric guitar with your effect pedals plugged in-line between your guitar and amp.
The answer is yes. You do need a working 9V battery installed at all times to hear sound coming out of the main output, even with the OBEL bypassed. The pre-amp is always active in the signal and the pre-amp is powered on by plugging in a guitar cable to the main output. To save battery life, unplug the guitar cable when not playing your guitar. If you accidentally leave the cable plugged into the guitar, the battery would drain out in about 2 weeks, that's about 14 full 24 hour days of battery life from a single 9V.