A certain amount of condensation seems to be par for the course with some pods. All I do with mine is wipe them out with tissue each time I refill them.
Condensation is OK, but a full leak which you will recognise when and if it happens is a different matter ... however some coils can suddenly leak as if a dam had burst when they come to the end of their life, so if a leak occurs my first thoughts would be to change the coil first and see if that solves the problem.
Being honest - a lot of vaping is learning as you go along, and the wisest advice I ever got when I joined was - "always have a back up for your back up!" It might cost you money but keeps you off of smoking.
As a final - if your coils have a recommended wattage - it's just that, a recommendation and no more - it's ok to start lower, and if you like the vape you get there it'll do no harm to stick with that setting.