Ah, much better questions, my friend. Most everything one buys is only due to preference, and or trial and error. I prefer the Speedplay type cleat, but there are several other types, such as the Look Keo type, or the egg beater type. Or, just plain pedal, with/without strap. All preference. Everyone here will give their taste. As for tires. Again preference. I was a Continental Gatorskin user, until I tried the Vittoria Diamante Pro. I'm a distance rider, I want a tire that is dependable and forgiving if I inadvertently ride through broken glass or rocky road. Get a tire that is VERY RELIABLE! PERIOD!
Computers; you can't go wrong with a Garmin.Most all of them are very reliable, or, use your smartphone with a tracker app, like Strava, or Mapmyride.
Are you going to ride distances? Again, start out slow, sorry, build yourself up. Distance riding is awesome! And to mix that distance with bike packing for overnight camping is great! Best to you