Let's say you got 2 bred does and each had a buck and a doe. The following year you could breed the buck from one doe to the other, or the buck from one doe to the doe fawn from another, etc. I think that was the point Wild Rivers was trying to make.
As far as average fawns I would say two. Normally, if a doe fawn gets bred at like 5 months she will only have 1 but it varies. Usually, my mature does have two but sometimes you can get trips.
The basics of AI are as follows: there are two options, conventional and Laparoscopic (LAP AI). With conventional you usually put a whole semen straw into the doe to breed it but you can learn to do it yourself so you could save some money that way. However, with Lap AI, a vet comes to your farm and performs a laparoscopic procedure to inseminate your doe which costs about $300 per deer. One big advantage of Lap AI is you can have the vet split the straw 2,3, and sometimes 4 times so if you paid $1000 for a straw and put it in 3 doe, you would have $1900 wrapped up in that breeding.
Regardless of the options there are some things you have to do to get the does to cycle at the precise time of insemination but you can learn those details later.
You have a lot of good questions and you're on the right track.