How do I use depuis, pendant and pour correctly?

Starting off with 'depuis', which means 'since' or 'for': it is followed by a verb in the present tense and refers to an action which started in the past and is still going on in the present, for example: J'étudie le français depuis trois ans (I have been studying French for three years- I still am now). Another examples includes: Il conduit depuis quatre heures (He has been driving for four hours and still is). Whilst 'pendant' also translates as 'for' in English, the action is one that is started and completed with no relation to the present (there's a specific time frame) and it can be used with present, past and future verbs. For example: "J'ai étudié le français pendant trois ans" (I studied French for three years but I don't study it anymore). Another example: "Je court pendant une heure tous les matins" (I play football for one hour every morning- set period, no relation to present). Unlike 'Pendant', 'pour' can only be used to express a duration in the future "Je serai en France pour un an" (I will be in France for a year), "Il chantera pour une heure" (he will sing for an hour).