Be sure to get the matching AC adapter. I'd recommend two of them and then two rapid chargers. Wall charging is much more reliable than USB charging.

I will not comment on the juice selection. You will figure out what you like soon enough. A bottle of PG will help water down the concentration if it gets too strong.

I didn't know that the eGo passthrough now offers unregulated voltage as an option. These look interesting and will likely serve you well.

Get a few extra drip tips as they are cheap and will help keep your half-empty cartos dry. Even if the spare cartos already come with the basic drip tips, a few coloured ones will really improve appearance.

Ensure you will be able to refill your cartos.

The cone shaped covers will not cover your 510 cartos completely, they are designed for just atomizers as far as I've seen. They may fit well around your carto though, while improving appearance and serving to reduce occasional overflow drips.