A1: Well, you only can mix ingredients using alchemy, you will unlock at the third chapter of the game.
search any alchemy guide at "google"
but I can introduce you for alchemy
first, you need to have an jar, and ingredints
thw jar have 5 numbers, that is the effect of the item you will make
example
if you have an jar:
0 0 0 0 0
and add an health mushroom, you will have this:
0 0 0 0 +2
an item have 10 effects,
5 positive:cure,strenght,potence,speed,health
5 negative:confusion,weakening,amnesia,unconsious, and explosion
example, if I have an jar:
0 0 0 0 -5
ill have an explosion item
but if I have
0 0 0 0 +5
ill have an healing item
the effect of your itens is represented by the number and the positive/negative simbol
the effects can be better adding more itens, example
the first, second,third and fourth compound have more duration with the level
but the last compound have its effect strenghtened adding more itens at the mix.
some ingredients have more than one component
example
if I have an mushroom:
0, -2, 0, +10, -21
this will be an explosive mushroom, if I add it to an ampty jar ill have an explosion mix -21
to make an iten ill need to add another item that will finish my mix with an useful item
i can take the mix with an:
Flask
Esphere
Sushi

the flasks is useful to use in yourself or if trown it will explode
the espheres can be trown and bounce and release smoke
the sushi can be eaten by one enemy

now that you know some alchemy, lets do an simulation?

i have an jar:
0,0,0,0,0

i add an mushroom 0,0,0,0,+1=
0,0,0,0,+1

i add one herb 0,0,0,0,+5
0,0,0,0,+6

i add an mushroom 0,0,0,0,-10
0,0,0,0,-4
i estract using an empty esphere:
i got the item:
Esphere
0,0,0,0,-4
that is an explosion esphere!
i hope this "little guide will be useful!
good bye!
credits: akuma95