Roads don't have to be run to every place but I have found its best to do so simply because your workers and construction people can get there faster. I always build at least two construction buildings and as many garages as needed. The game will tell you when you don't have enough garages.
To say the game is not complex is not true. Its a matter of how complex it is. To some its very complex, to others it is not, and some find it somewhere in the middle. I, myself, fall into the middle of it. I find the campaigns harder than the sandlot games.
Also, tobacco, sugar, and coffee make for the best export products when it comes to farming.
Ponti, you may find it easier to learn by doing the sandlot and making a really easy island with lots of resources to learn the mechanics. Thats the way I ended up going because I found the campaigns hard. Even the easy ones.
*SPOLIER WARNING!*
CHEAT METHOD MENTIONED BELOW
*LAST WARNING!*
I'm not going to argue whether cheating is good or bad. If you dont want to hear about it then you shouldn't be reading this part. So don't start whining about cheaters!
Okay, lets say you are still having a hard time with this game. Money is probably the biggest problem in this game. Never can get enough or get it fast enough. Here's how you can get the money cheat to work. While in game just type 'muchopesos' on the keyboard. You won't see the text on the screen when you do it so just type it out. As soon as you do your balance jumps up $100,000. You want another 100k just type 'muchopesos' again and each time you do that it will add 100k to your balance.
Now the reason I mention the money cheat here is if you want a easier time of learning the game you can make a sandlot game. Make the largest island, make it flat, and with lots of resources. Choose whatever avatar you want. Fidel is a good ready made one I have found for most any game but there are others you can try. Now do the money cheat once the game starts and get yourself a couple hundred thousand pesos in your balance and then start expanding the already started city. Add buildings, roads, farms, mines, etc., You can pause the game first while laying out the grid work and then when done unpause the game. When you lay down the building just set it not to build. As you need the buildings just set it to build. Its best to just go one building at a time so your construction workers are not spread too thin. This is one way to learn the game from a very controlled method of cheating. Experiment as you go. Make some save games of your progress.
This is a quick and dirty way to learn how things work in Tropico 3. Once you think you got a handle on how things work go and start a regular game without the cheat.