The blue bits are commercial not industrial, you'll need industrial first (as with other sim city games). Its probably not developing because it is too close to that power plant, the pollution will put the businesses off. I tend to build the power plant right in the corner of the map away from anything as it always lowers land value. Or just build wind farms instead, especially for a small town.
You need to build roads over your streets, (roads are black, streets light grey) this will allow sims to travel further for work, it will also reduce congestion. Putting in a bus network early on can also help but as your strapped for cash perhaps not the best idea.
Farms will only make a bit of money, however their benefit is they can hold quite a lot of jobs and do not pollute the air ( they do pollute the water though) as youalready have light industry id stick with that. Move it a bit more away from the residential areas and build roads. You should see the land value, and therefore tax revenue increase. Anything else ask away, hope that helps a bit.
edit...joining neighbourhoods, just build a road up to the edge of the map and it will ask if you want to make a connection.