Welcome to a great way to getting around.
Most people recommend a change in saddle. Hopefully your dealer can help fit you to a saddle. You may need to shop a dedicated bike shop (REI stores do a good job).
I purchased the Jumper, because I wanted full suspension.
Try riding awhile before changing derailleurs.
I hope you will report your experience going forward.
I'm considering the light harness, but there are a limited number of 6 volt D.C. lights available.
Drivers routinely misjudge how fast I am moving and pull out in front of me; I use two front white blinky style lights and think drivers see me but misjudge speed. It happens much more frequently than when I've ridden motorcycles.
It's actually not a big deal since the e-bikes allow us to get back up to speed.
Padded bike shorts are a good idea. The Pearl Izumi Attack work best for me. I do wear them under my jeans (and you do wear them without underwear).
Do go over removing the battery with the dealer. They can be tight. I often use a pair of plastic levers designed for fixing flat tires. If it is too tight the dealer should be able to adjust the fit.
Mike
Colorado