Piano purchasing and the research that goes behind it is an activity best taken when not rushed. However, I understand your immediate need of a practice instrument for school.
If you have an idea of the sound and characteristics of the piano you desire, this may help shorten your list. However, if you are just listing these pianos without having experienced playing them or similar of the same brand it is best you do so before considering them. Play lots of pianos, eventually you will hone in on the characteristics you like to have in a piano.
Since you seem in urgent need of a practice instrument, I'd go for a less expensive one in good condition. You can upgrade later on to a better piano when you have had a chance to do more playing and research.
If buying used, always get a piano technician to check the piano. There is a fee for this, but it is a lot less than finding out you paid for a $200 piano when it needs $1000 in repairs. You don't want to be frustrated with a pianos problems when you are trying to get some practicing done, so make sure it is in good working condition. The tech will help you with this.