Welcome to the forum!
1. Do I need an "E" rated LT tire
This is a ply rating, or sidewall strength
rating of the next higher class tire: "LT". LT's do come in other
ply ratings. E=10 ply, D=8 ply, C=6 ply.
I like the Bridgestone Dueler Revo's. They come in both 'P' class (passenger
car) and 'LT' class
Again, the 'E' is just the number of sidewall 'plys' from the old days. Today
tires normally have 1, 2 to maybe more sidewall plys
Going to the next higher class tire will have 'LT' tires require more PSI to
carry the same weight as a 'P' class tire. So, check your wheels to make sure
they are rated for them
Also note that 'P' class tires used on pickups are required to be de-rated a min
of 9% of their sidewall listed rating. Whatever your truck came with from the
factory...the OEM has already calculated that de-rating of 9%