Now I know cavalry can't fire, artillery can't inniitate melee and infantry can't charge or innitiate melee against cavalry, that said...

Can cavalry provide melee support to infantry and vice versa?

Can artillery and infantry provide fire support to each other?

I assume the answer to both questions is yes.

Hi!

I assume too.

The rules say: "...units belonging to the same group may attack together..."

So, if you have a mixed unit group, there is currently nothing in the rules prohibiting this.

The official scenarios have no mixed unit groups, so far.