Since I'm alone on forum now, here is what I find out so far:
(and since I'm still alone I'll edit this same post)
When stock bar, harvestables are used in order they are in bar, meaning, what is first in line, will be used first. This seems random. I put 3 pepper, 3 onions, 3 potatoes and 3 garlics. First drink is made with pepper and onion. Second with pepper and potato and third with onion and potato. Garlic is ignored as well as plasma fruit, but my Sim is not a vampire so maybe there is a way to use them. Also, later I added 11 life fruits and 6 flame fruits, and he kept using life fruits until the last one. With other fruits it repeat the pattern as with vegetables, mixing them and using without order.
All mood drinks are created with 2 ingredients. EDIT: it can be created with one and still have a name. I put only one pomegranate and still got extra tropical crazy drink.
They look same regardless of items used in creation (no additional glowing, flames, sparkles etc).
Apples and watermelons made no difference at all. Party drink is still just a Party drink.
Limes in drink made them into (name of mood dring) with a Twist.
If vegetables are used, drink get the name (name of mood drink) with Veggies. That is how I first got Sorrow Annihilator with Veggies. Veggies are salad, tomatoes, onion and potato. Pepper will add (name of mood drink) con Chili. Party drink made of onion and pepper is named Party Drink con Chili with Veggies.
If any type of grapes is used (regular of French) drink is named Bacchanalian (name of mood drink) and that is how you got for example Bacchanalian Crazy Drink.
If using Cherries or Pomegranates (and I yet to test Plums and Pomelos) Drink is named Extra Tropical (name of mood drink) EDIT: tested and yes, plums and pomelos are also extra tropical
If using Flame fruit, drink is called Burning (name of mood drink)
If Life fruit is used, drink is called Lifegiving (name of mood drink)
If combination is used, all names are added, depending of which ingredient is used first. So if you use one life fruit and one flame fruit, in that order, drink will be named Lifegiving Burning (name of mood drink)
Flame and life fruit didn't get additional moodlets (cosy fire nor full of life), it seems that only change is in the name. if drink contain one life fruit, Sim's lifespan is extended (message sad it and in this test game I stopped aging so after all testing my YA now have 28 till Adult on normal lifespan).
If drink is made of 2 life fruits than you got 2 days from one glass. If one fruit is used, then you got one day per glass. This means that one life fruit can be used to extend life for 4 days.
And if you put cursor on glass you can see which ingredients and in which order are used.
All this is the same for unique drinks as well, name prefix and extended lifespan. I have no idea how it works with recipes from bars, but there is an option to choose ingredients for next drink.