All battery types are capable of venting including common household types such as carbon-zinc ( aka heavy duty ) and alkaline, though these are less likely to because their chemistry make-up isn't as volatile like some types of lithium-ion batteries. Since certain types of these are less stable, they add a protection circuit to the larger of them that protects against common dangers, such as overcharge, overdischarge, short-circuit (overcurrent), and temperature.
An 18650 is actually a type and size of battery... not a type of mod, though many different mod's use them.
Joyetech has one as an example usually refered to as the eGo 18650 ( GV calls them a eGo-T Mod ) that operates in regulated or unregulated mode. In regulated mode, it operates at 3.3v until the batteries are depleted, in unregulated mode it starts operating at 4.2v with a fully charged battery and as the battery drains can go down to 3.3v. This is a quality built mod which many like quite a bit.
There are replacement heads for the eGo 18650 mod but currently GotVapes doesn't list them seperately.
Bolt is another 18xxx size battery mod which can take several sizes of batteries. By default it is made for 18490-18500 size batteries and with an extention can fit a 18650 battery also. Also using the extention, it can fit a 18500 battery with a Kick module which adds regulated variable wattage options... use two extentions and you can use the 18650 battery and Kick module. Without the extention, the Bolt operates in unregulated mode only.
GotVapes also carry a few variable voltage mods that also use these size batteries.
I mentioned the Bolt to harleydiva so she would take all of the options available from GotVapes into account and be able to select the one that would best fit her needs. There are other mods that use these size batteries available from different vendors as well.