I am looking to create a script in where I can adjust materials in dynamo just by typing in the corresponding number from the list. Am I going in the right direction?
Almost there. Use GetItemAtIndex with the number from your list of material names to get the desired material from your materials list. Then plug the resulting material into the SetParameter node. Another approach would be to use Elements.FilterByName from package Clockwork to retrieve the desired material by typing its name.