Water Flow App (Newbie)(Geometric Network)

[JonGarner]

So first off I am completely new to ArcGIS, I'm a CAD guy.... 

I've created a stormwater flow map, using Civil 3d for a client. They are interested in some type of map that they could click on a line and it would highlight the flow line all the way to the destination, this idea was recommended by someone familiar with ArcGIS but they aren't sure about how to go about this problem.

I've been playing around with ArcGIS/Map and sounds like I could use geometric networks and network analyst to do something like this.  First off would this be the best solution to this problem, if not can you point me in a direction about what would be a better solution. 

Secondly, how will I end up getting this in the client's hands(they have no GIS software).  Will it have to be some web based app, or is there some type of free viewer?  Also in regards to this app, will it involve some type of scripting to make it work like I want or is this type of functionality built in to ArcGIS and they're web app system.

Lastly should I be attempting to do this using ArcGIS or ArcMap?

I know that's a lot of questions, and any help would be appreciated. I've been googling like a madman, trying to figure out where to get started learning on all of this, and trying to determine if I can set a feasible goal of learning all of this by March. 

[omega_cancer]

click on a line and it would highlight the flow line all the way to the destination,

Feature service and editing does it by default

geometric networks and network analyst to do something like this

These tools work with Arc Desktop and can be exposed to client on map using GP tools.

how will I end up getting this in the client's hands(they have no GIS software)

But I assume that you have ArcGIS server licence and you are legally allowed to publish and make your clients consume it.

Will it have to be some web based app,

Yes

or is there some type of free viewer?

Free Viewers are available which require no code at client end to accomplish your task provided your services are ready.

will it involve some type of scripting to make it work

Javascript and ActionScript

Look at my above paragraph

like I want or is this type of functionality built in to ArcGIS and they're web app system

Silverlight

ActionScript

JavaScript -- Famous and future of rest of all

Lastly should I be attempting to do this using ArcGIS or ArcMap?

ArcGIS is the name of the suite while ArcMap is a software in it that deals with creation, edition, manipulation and publishing of data.

There are a lot of questions. To best of my knowledge and description provided by you I would like to go with Web app.

1. Create a Feature service using ArcGIS Server.

2. Publish it on a location where your clients can access it.

3. Create a web app and use Web Editing Functionality provided by almost all ESRI Web Mapping APIs to allow clients to edit and explore them.