As far as EMP goes. I don't know enough about it. Would grounding circuits making a low resistance be better than leaving them open?
Any semiconductor junction outside a well designed shielded room (Faraday cage) will likely be blown. Grounding matters, but only accomplishes much if attached to said shielded room.
To 90s question - not much, as anything meaningful (obtain significant water, food, mechanical only equipment, tube operated electronics.....) would typically take much longer. I'd fill up as many vessels as I had with water, but that's probably it. (Yes, I realize civilians won't get the headsup in time...)
The EMP area would end up circa 1880, less telegraphs.
90 does have a point about prep though (often not easy to discuss publicly, w/o being labeled a wingnut though.....), as most of us take our modcons for granted. Another Carrington event will happen; it's just a matter of when.
Rgds, D.