The rules are as follows.
Carry on liquids are limited, and that includes eliquids. Put them in the 1 litre bag with your emergency toiletries and drugs.
There is no limit to eliquids in checked-in luggage.
Devices are probably best carried in carry-on, since you can explain them if they raise a concern. That's what I did, and I did have to show one mech mod once. (Leaving the UK) They thought it was an e-cig, but wanted to check.
Batteries that are not in devices must be in carry-on, and they must be protected against accidental short-circuits. The recommended way to do that is to put them in battery cases or in their retail packing.
Bottles of eliquid will probably survive OK, but filled tanks will probably leak due to air pressure changes. You will want to bag them.