yes because it is not what it means. "once" means "one time", not a full day per week.
Is it correct that the "s" in cours is mute even though the next word starts with a vowel?
Does it depend on the word? I've noticed that some words do and some don't pronounce silent letters before vowels...
Maybe have a look at this: http://french.about.com/library/pronunciation/bl-liaisons.htm
"once a week" is the time marker pointing to a habit, hence simple present.
Yes, it is wrong. Although Je cours can mean I am running or I run. In English they do not mean the same thing. I am running means that is what I am currently doing at that moment in time. I run does not refer to what I am currently doing, but that I repeatedly perform that activity (running) and will continue to do so. Clearly this French sentence is the latter meaning.
I wrote: 'I run for a time per week.' I'm aware its kinda wordy but shouldn't it still count?
I run (exercise) = I jog (?) or it's a race horse's statement?