Portraying Features in the Database

Imagine that you did do such a great job consulting and developing the town's first GIS database that the Public Works department, at first skeptical about GIS, has seen the light and would like to create a GIS database for their utilities (water, sewer, and drain). They have also decided to make GIS a priority and are ready to make a substantial investment in data and technology. That's the good news. The bad news is that the data you had previously collected no longer suits their needs and they would like to develop a very detailed database. The town has provided you with a series of paper plans that show the utilities for each street in town. Some of the plans are in poor condition and some have not been updated in several years. After meeting with the clients we have learned that the utility wants to focus its initial data development efforts on the drain utility system. The mapping for this system must contain the following elements:
Drain System
Manholes
Outfalls
Pipes
Culverts
Inlets/catch basins
Detention Basins (these are small above-ground "ponds" that store stormwater runoff)
Drainage Areas (these are areas defined by topography that contribute runoff to water bodies)
The client also wants to begin developing a "landbase" feature set of layers that must contain the following features:
Parking Lots
Roads
Street Centerlines
Driveways
Forested Areas
Buildings
Water Bodies
Topography
The client wants to be able to count the number of features in the database, calculate areas, etc. How would you portray each of these features in the database (points, lines, areas, rasters)? Do you think it is wise to group these features into separate databases (one for landbase features and one for drain system features)?