nogareaux,
Okay as one ABC to another. I will assume you are girl and not a guy. Since guys like us suppose to be drafted if we goto Taiwan for too long. If you’re a guy have enough money to buy a round trip ticket back to Taiwan every 4 months. I thing HK is the cheapest destination and back.
You cannot work legal in Taiwan as a foriegner without an ARC. You maybe able to get around this by entering on you Oversea’s ROC passport. I have no idea about this. Since I would be drafted and never done this.
Let’s say you cannot enter for a year on your oversea’s ROC passport. Then you back in the same boat while entering on your USA visa. You need enough money to leave the country every 4 months and re-enter like every other foreigner on a vistor visa.
Let’s look at income. What’s the going rate for rate for ABC tutors and English teachers in Taiwan. I don’t know it’s been almost 8 years since the last time I did this and I’m 7 years older than you. But in the papers I see ranges of 300 NT to 1000 NT an hour from a quick glance at the help wanted section. I have no clue what people in Gaoxiong are going to pay.
Don’t forget to factor in reverse descrimination for being asian. Taiwan native have no clue what you’re english skills are. You take a test and then they look at you. If your chinese is crappy maybe they’re buy the story you’re an ABC.
There are two routes for English Teachers. Get one steady gig at a Buxiban under contract, which is like 15,000 - 30,000 NT a month. Or try to freelance it with many as 2-3 buxiban and 2-3 private tutoring.
Then there is rent. You mentioned a friend. How long can you stay for free. A whole year? That’s great.
If you live on your own and you live Japanese style or in a Student Dormitory area (Bei Shu) you might be able to get away with as little as 7,000 NT I hear. But don’t expect much. I’m talking tiny by USA standards. If you get your own bathroom that would be great too.
Food is cheap as dirt here. Night markt stuff. Or “Chi dao Bao” will be your favorite signs on local eateries. The cheaper it is the less questions you want to ask.
When I got really desperate one month I broke it down to 11 NT for instant noodle with their own bowls. 8 NT for instant noodle with no bowl. 1 NT for an egg. Hot water free - stole it from the school.
The nearest Chi Dao Bao noodle shop was 80 NT for a bowl of shredded meat noodle soup. Eat as much noodles and drink as much soup for 80 NT in one sitting. I once saw a big hapa Chinese guy eat like 13 bowls of noodles on a mere 80 NT . 
I think if you live a very humble lifestyle you can make it on your own without family wiring money to you every month. No Air conditioner, no motorscooter, no KTV, no MTV, and not too much partying in the city.
If you think of Teaching English in Taiwan as a burger flipping job stateside, and moderate your lifestyle to what a burger flipper would live like stateside by themselves. That’s basically it.
Is it fun? Very fun. Should you do it now? Definitely, since you’re young its the best time to do whacky stuff like this. Then you become an old foogie like me and have a bunch of kookie stories to tell. 