Do start in the ECF library and read The Wonderful World of Vaping. It will answer a lot of your questions.
The ECF Library - E-Cigarette Forum
The basics:
Stock batteries require very little initial investment but if you find vaping is for you, you will quickly tire of having to charge and change your batteries every 1-2 hours.
The eGo (which works with 510 cartridges and cartomizers) will last longer and cost a bit more. For an even larger investment, you can get a mod with a long-lived battery. I don't think anyone can drain an 18650 in day.
e-Cig Mod Battery Chart | e-Cigarette Battery Comparison
Cartridges - The filler isn't perfect. Be prepared to play with straws, Fluval, etc. But cartridges go with atomizers which easily last a few months (unless you buy a dud.)
Cartomizers - Combination cartridge & atomizer. Much cheaper than atomizers but also more disposable.
Whatever connection your battery has (510, KR808, 801, 901, M4...), you won't be making a lifelong commitment. Adapters are available which will let you try other atomizers or cartos. So don't worry about making a few mistakes along the way. Most of my "rejects" are tucked away for emergencies.
After 7 months (tomorrow), I've settled on a
Little Chuck with soft tipped 510 cartomizers from
Clouds of Vapor (I think they have the best price) and a drip tip (COV carries the ones I mostly use but
Nhaler has the most beautiful selection.) For liquid I vape
Tasty Vapor almost exclusively.
I hope that helps. Good luck on your vaping journey. You're gonna love it.