It is an interesting ad. Well what stands out for me is that I do not think that it is written by a native speaker as there are a few grammar points that are not normal for a native English speaker. There is no apartment provided, you must get your own. There is no year end/travel/airfare offered and this sliding salary is all promise! Ask for references from teachers that are teaching there or have taught there is the past and talk to them before committing.

That is my take, good luck.