Create a self filling GANNT Chart

Hi,

I am trying to create a pipeline and projecting took for our company which includes a Gannt chart. Now, what i want to do is make this as simple as possible to fill out for the users (we are using this on google docs as a collaborative tool). I have included the file below. Now what i want to do is this:

1. In the "H" and "I" columns i would like to (if possible) have a calendar pop up for selecting dates (like on many web sites)

2. In the columns between AD and CP i would like to color in for the corresponding dates to 1.), the color will be selected based on the selection in the D colomumn (Project manager)

Is this at all possible to automate in excel (google docs), and how would i go about doing so?

All help would be greatly appreciated!