You'll be wanting a job then?
Try not to work all week on a hourly flying wage, especially if you have little cash reserves in the bank. Salaried jobs are rare is seems.
How did the position become available? If instructors are leaving for other schools, is that a problem?
Ask what what their induction plan is for a FI(R); you'll at least need to know how compatible your training is with the school's.
Ask other instructors how many hours they did last month, in the last 6 months and last 12 months.
Ask if any ferrying work is paid.
As a FI(R), ask how much per hour is removed from your flight pay for "supervision" (I kid you not)