Public toilets get called: toilets, conveniences, WC, Ladies, Gents, restroom, washroom. In your house you might refer to them as: the toilet, loo, bathroom. There are loads of other words that get used in certain areas and by certain people, for example 'the john' 'the lav.' The word 'latrines' tends to be used by the military. I have no idea why we have so many words for toilets. Perhaps because they come in so many shapes, sizes and varieties. Some are just toilets (the bit you actually use). Some toilets are in bathrooms. Some toilets have other facilities such as showers or baby-change areas (for changing nappies/diapers). Some toilets are just for ladies, or just for men.

Yes, "WC" seems to be a Europeanism... I'm used to pronouncing it as "vey-tsey", like a central European. Basically, we use so many euphemisms for toilet (even the word "toilet" is a euphemism) that explaining each one would just confuse you. Bathroom, restroom, lavatory, or toilet will be fine for regular use. Listen to what native speakers actually say (I mean, in a real conversation - this isn't something you can learn from a book or an explanation). If you're really not sure, just use "toilet". You'll also hear " the gents' " or "the ladies' " to refer to public toilets.

WC (meaning 'water closet') is something that I only ever saw in Europe. It is the only one of all the ones that you mentioned that would probably confuse a person in the United States. Of those, the ones that are common around here are bathroom and restroom. Toilet refers to the actual part of the bathroom where one does their business. I believe that 'latrine' refers to a site of similar utility that is much more basic, like the ones you might see at a camping site.