I read around that formatting your memory card will shorten its life.
Nope, not in any meaningful way. Deleting files will perform more writes to the card than an in-camera format that just sets the file table as empty.
Plus the amount of data written by taking photographs so far exceeds the data written with either a format or mass file deletion that which you do is functionally immaterial to card lifespan.
Why format the memory card in the first place? Why insert the card in the computer when a USB cable will do? I have had a 64GB memory card in my Canon Camcorder since 2018 and it still works great! Everything is backed up of coarse.
Formatting in the camera ensures any spurious stuff written by the computer filesystem doesn't cause an issue with the camera and also avoids any sort of filesystem hiccups from file deletions. While it's unlikely there'd be problems, better to be safe if you're going out for a day of shooting. Remember that while computers perform filesystem validation/repairs, cameras do not (AFAIK)
Cord vs cardreader is a matter of personal preference. In my case it's faster to open the card door, grab the card, put it in my dock's card slot than it is to open the fiddly rubber cover over the camera USB port, plug in a USBC cable to camera and computer, turn on camera, then select Storage mode for the computer to see the cards.