I found one of the easiest ways to simplify the game without hacking or removing many sources of Fun is to lower the population cap. I found that once my fortress grew to 100 dwarves or beyond, I couldn't figure out how to manage all of them and keep them working productive jobs. So instead they all just sat around throwing parties and pestering my productive dwarves. Until you get enough experience to handle a fortress that size, try lowering the cap to 40 or 50 dwarves.
To do this in v0.31.08, edit data/init/d_init.txt and change the value of this line:
[POPULATION_CAP:200]
Note: your actual population may still go above the cap you set, you just stop getting new immigrant waves after you reach or surpass that cap. And apparently births don't respect caps. Also I think (but I haven't tested) that you can change this mid-game if you save and quit first.
This is a complicated question, so I'm going to distill the basics and point you to Wiki entries for specifics.
Let's say for example you want to make an iron bar and have nothing but the required raw materials. First you need fuel (assuming you don't have easy access to magma).
Fuel
Fuel is either charcoal (from wood) or coke (from lignite or bituminous coal). Charcoal is made at a Wood Furnace b-e-w by a Wood Burner. This requires one wood. Production is one charcoal
Coke is made at a Smelter b-e-s by a Furnace Operator. Ingredients are one fuel and either a lignite or a bituminous coal. If lignite, the production is two fuel. If bit. coal, the production is three fuel.
So bit. coal is the fastest, most efficient way to make fuel if you have access to it. The trick is in order to start making fuel from bit. coal you need one unit of fuel, so you'll usually have to make a charcoal first.
Details here: http://df.magmawiki.com/index.php/DF2010:Fuel
Metal Bars
Now that you have fuel, you can convert your iron-bearing ore to iron bars. Metal bars are made at a Smelter by a Furnace Operator. Ingredients are one iron-bearing ore and one fuel. This produces one iron bar. (Iron ores are limonite, hematite, and magnetite.)
Iron is simple, but metal alloys like steel have a more complicated process. The Dwarf Fortress Wiki is your best source for specific info there.
List of various metals here: http://df.magmawiki.com/index.php/Metal
Best Answer
Dwarf fortress already has a square tileset available to you. Simply access your DF graphics folder and copy the name of the square tileset. Then search either init text files (in the DF folder) for the tileset option (it'll have the base tileset name so you could copy that files name from the graphics folder to accelerate your search). Once you've found it, replace the existing entry with the name of the square tileset and voila, original DF look with square tiles.