What do I need to know to assess land value

[Seth Sandler]

I recently came across a very large (3.5 acres) undeveloped plot of land in Los Angeles in a residential neighborhood. The property is zoned as a LAR1 and seems plenty big enough to subdivide into at least 2-6 lots. The land does have a Storm Draineasement running through part of it and it's not completely flat. The price seems very low considering its potential for building. However, I'm completely new real estate.  

Who would I need to contact in order to know:

1. Can the land be subdivided? If so, into how many plots?
2. What can be built over the Storm Drain easement
3. Any other limitations/factors/etc

The land has been on the market for 55 days and had a pending sale a month ago that fell through. It was last sold in 2016 for more than half of what they're asking today. What are the right questions to ask and the right people to talk to in order to evaluate this land?