can the update be installed from the saved exe file downloaded from SD?
Yes.
how can 7.2 be archived just in case. (impulse?)
If that is the version shown as currently installed in Impulse, then yes. If not, then not unless you have archived it previously.
Archive 7.2 , then download 7.3 from the store. The one in Impulse was still not fixed as of this morning.
