Welp, basically ga is added as a subject marker after a vowel. This is when something specific is being said. Like the cat is an animal. Sorry if im wrong, this is just me pouring all the current knowledge I have out.
You can download an korean keyboard from your settings! Well, depend on what kind of phone you got, but it'll allow you to flip through the two languages by using the space bar button (you'll see what I mean)
My translation is better. It is more likely that a person in conversation will be reporting a current event or an immediate future event, such as a scheduled one, than a recurring event, which is what the simple present describes in English.