To be honest I have absolutely no idea. What difference does the size of the thing make? Battery life I don't know... I was under the impression you could charge them anyway.
Sure - everything is rechargeable. But the smaller the actual size of the battery the smaller it's run capacity. You can only cram so much battery goo in those tiny cigalike batteries, so to speak. And that's one of the biggest annoyances with cigalikes: having to recharge that type of battery every hour of use gets real tired, real fast. You can easily run into a dilemma where the run time of a cigalike is between 45 to 90 minutes, but it can take nearly two hours to charge. And that's a problem.
Very roughly, a 180 mAh cigalike battery? 45 - 90 minutes run time. A 1000 mAh eGo style? A good 8 - 10 hours run time between charges.
One weird question I have which probably sounds stupid... when you smoke a normal cig you finish it and throw it away. How do you know how to stop with an ecig? Do you just smoke till you've had enough?
Not weird at all. There are many aspects to the "vaping is not smoking" learning curve. That's just one of 'em! But I'm not sure which question you are asking: How long do they last, that is until they fail? Or how much/how often do you use it?
If you meant how much/how often? You have to dive in and sort it out. It can depend on how heavy a smoker you were... There is no hard and fast rule that everyone absorbs the same amount of nicotine from the experience... And we don't have any easy way to factor "if I smoked this number of that brand, how much vaping does that equate to?"
As part of the "vaping is not smoking" trade off you actually have to work at vaping enough when you start. The cues you used to get from smoking aren't in play. There is no lit cigarette generating smoke and reminding you to use it or waste it. You actually have to pick up your e-cig and push a button - in that way there is no auto pilot like with smoking. You are shooting for overall consistency in your vaping experience throughout the day. You don't get those instant nicotine rushes out of an e-cig like you do with smoking, so trying to chase cravings doesn't work very well as an approach, especially when you are trying to quit smoking.
It's not as complicated as I just made it sound. lol Just keep in mind that it is different from smoking so there are a few things to adjust to.
Welcome!