Probably at least the following:
- Cost
- Expected from net price calculators or list price or automatic merit scholarship
- Actual if you have the financial aid and scholarship offer, or
- Majors of interest offered
- Accessibility (i.e. how difficult to change into them, or if there is secondary admission)
- Admission (including to major) and affordability likelihood estimate
- After admission and financial aid and scholarship decisions
- Admitted and affordable → becomes safety
- Denied or admitted and unaffordable → becomes out of reach
- Admitted with financial aid and scholarships pending → change to chance of affordability
- Waitlisted → becomes high reach
- After admission and financial aid and scholarship decisions
- Anything else you consider important
In terms of number of colleges, if you have an affordable safety that you like, you can eliminate applying to any college that you like less than your safety (i.e. you will not choose that college over your safety under any circumstances).
In terms of application materials, there will be some shared applications (e.g. UC, CSU, The Common Application, etc.). But sometimes (particularly with The Common Application), a college will have its own unique supplements to do. So your spreadsheet may want to include a line for each type of shared application, then indicate how much work each additional college will be if you already do the work for the shared application.