My issue is around
1. Create a thriving fortress.
My fortressess generally live for a few years. just until immigrants and children start to put unbearable strain on my soul. Migrant waves of around 50 dwarfs are a sure way to abandon fort.
About verification: we can mark critters by burning their feets with magma. like making them to make a few steps in 1/7 magama should be enough to mark our animals in a unique way.
Other option is to chain them and destruct chain with a lever. this way animals will leave our site with rope around the neck.
in df folder - data - init is a file named d_init.txt. Here are soe general settings you can toggle such as weather, temperature, invaders and also, population cap (pop-cap). This will not stop migrants comming at exactly the point you set. Only when the liaison arrives, has a succesful discussion with your mayor/baron/expedition leader and leaves the map unharmed, will the liaison report you don't need more dwarfs.
Set it at 50 to recieve the 2 hardcoded waves + 1 year, 80 for another year. 80 is taking in account some casualties. In a no casualties fort with some wealth that usually will end you with 100+ dwarfs.
While you are there, you might change the child cap. After all, you don't want the married women mass-producing babies. One is a number cap, the other a % cap (forgot which is which). The number cap says "when there are x children and babies, there will be no
new pregnancies. Similarly, the % cap looks at the number of adults and takes a percentage. so at 50%, if you have 60 adults, the max number of children and babies is 30. However, the cap takes the lowest setting, so if your number cap is at 20, that one will be active. Note that it doesn't prevent migrant children or existing pregnancies, only future, and setting it at 0:0 might deactivate it
Also, I might suggest using dfhack to give names to creatures