How many lumens would you suggest? WallyWorld has one with 120 lumens in back. They've got some full sets with up to 5000 lumens for the head light, but that's a bit out of my price range (over $200), and at least right now I'm just going up & down a residential street.

What I have has low/med/high/fast strobe in front, and steady/fast/slow strobe in back. The fast strobe front would catch people's eye for sure.

Something I might run in to on the back light is that my seat is all the way down, so there's not a huge amount of space. I saw one light on Amazon (Apace Vision) with a vertical mount tail light that wouldn't fit. I've got the headlight mounted under the handlebar.

Any advantages/disadvantages of external battery packs vs internal?

I've seen some lights with what they call 'overdrive' mode. Is that extra bright?

What about helmet mounted lights?