How to use cut or awk commands into sed command ?

[Halid Faith]

Let me try to explain
I have a file called A which contains variable values as below;
file1, abc12
foot1, cba11
boby, def123
...

Also I have another file called B which contains partly valuable values as
following;
### file of A begin
Server valuable1
Client valuable2
#### the file end

I have to assign the first column valuables in A to valuable1 in B and
assign second column valuable1 in A to valuable2 in B.
Finally I should see as following in a file called C
Server file1
Client abc12

Server foot1
Client cba11

Server boby
Client def123

How can I do that ? Could you give me a script ?

Also does it possible to define two or more variable in for loop as below
 for  i in `cat file1` a  in `cat file2` ;
do
sed -e "s/oldstring1/$i/" -e "s/oldstring2/$a/"
done

Thanks