Avocado are big trees. You can keep them in a pot for a while, but I don't know how long.
Use citrus food on the avocado, it works. Follow the label instructions. Trees are fertilized based on the diameter of the trunk.
You should remove the stake if the tree is stable. Staking trees prevents them from moving. Trees that have to bend more develop stronger roots.
Avocado 101: Avocadoes come in A and B types. Apparently there are some avocados that have both flowers on the same tree. Probably from grafting an A and a B on the same rootstock.
Avocados exhibit synchronous dichogamy. Avocado flowers will bloom for 2 days. On one day a flower will be open on say the type A tree and the female organs will be receptive to pollen from a type B tree that has flowers open in the male phase. The flower will close on the type A tree in a few hours. The next day the same flower will open in its' male phase and shed pollen to be carried by the wind or insects to pollinate the female flowers that are open on the type B tree.
This type of reproduction was intended to maximize genetic diversity. A normal avocado cannot pollinate itself since male and female flowers do not open at the same time. It is why most people get a grafted tree from a known producer, since like a box of chocolates, you never know what you are going to get.
https://ucavo.ucr.edu/Flowering/FloweringBasics.html