* Put everithing in written. It ensures that everyone understood the same thing and you or your frinend will not post here in 2 years about a big fight. "cuentas claras mantienen la amistad" (clear accounts preserve friendships) I'm not sure the best tranlation https://www.google.com/search?q=cuentas+claras+mantienen+la+... (Did you said 50% and 50% or it was proportionel to the time in the office? Did it included the previous years? No salary means more equity? Who paid for the new server? ...)

* 4 years vesting with 1 year cliff: How long have you been working in this? How long has ypur friend been working? Full time? Part time? Only a weekly free Zoom of 40 minutes?

* Who will make the angry calls to the contractors?