It is fairly straighforward to read and write multiple channels. In Measurement and Automation Explorer, hold the shift key and select the channels in the channel configuration tab. Then select the create item button and name the item. This
knowledgebase contains for information on how to do this.
It is possible to change the range of the incoming values. What exactly do you the conversion to be when you say that you want to change the engineering units?
Hope this helps!