Sisiutil said:
In terms of his "personality", I'm not sure what to expect--any insight there, gang? Is he a psycho like Monty, a religious nut like Isabella, a warmonger like Napoleon, or reasonable like Cyrus?
wioneo suggested that he's similar to Isabella. I haven't found that to be the case in my games. Brennus is the Isabella clone. If anything, he's worse than she is.
I've found Mehmed to be very similar to Cyrus and the other reasonable builder leaders. He's generally fairly advanced technologically (probably due to Organized), but he's usually not high on the power curve. Like Cyrus, he'll usually be in the top half of the scores but not #1 or #2.
Oh joy. Unless I can spread Buddhism to Japan, convert him, and run Mercantilism, Tokugawa is going to be about as useful to me as a snow-cone in a blizzard. The only time I ever saw friendly, tech-trading maven Mansa Musa destroy another civ, it was this guy--because Tokugawa is so obviously his antithesis. Mehmed may live longer just so I can go after Toku first and crush him like the bug he is.
Tokugawa is a tough one. I usually like to get rid of him either early or late. Early because he's not very useful as a trade ally, and he focuses pretty hard on his military, so he can be very dangerous as a neighbor. Late because if you do manage to keep him happy during the beginning of the game (fight a mutual enemy, for example), the gradual buildup of diplomatic points from religion, resource gifts, etc. can often turn him into an ally. At that point, he's so backward in technology that he can be a very safe friend.
(By the way, something about the graphics adjustments made in either Warlords or its patch makes the grid lines in world view more difficult to see on my computer. I don't know if anyone else has experienced anything like that, but if you have a solution, let me know.)

They didn't fix that? (sigh)
Someone mentioned lowering the graphic settings. That seems to work, but I don't like it. I like the high resolution graphics. That's a feature of the game. Why should I need to turn it off to re-enable a feature that Firaxis clearly broke. The workaround I use is "flying camera mode."
Open your CivilizationIV.ini file in an editor like Notepad.exe. This file would typically be something like C:\Documents and Settings\Me\My Documents\My Games\Warlords\CivilizationIV.ini. Find the "AllowFlying" setting and make sure it's 1. You should see something like this in the file.
Code:
; Allow Camera Flying
AllowFlying = 1
Now Ctrl-Alt-F will enable or disable flying camera mode. In this mode, the camera can be positioned anywhere (by moving the mouse), and for some reason the grid lines are drawn properly. This kind of reinforces the idea that the game engine is perfectly capable of drawing the lines properly and Firaxis broke it somehow.
The fact that any tiny mouse movement changes the camera position can make it hard to get everything in position for your screenshot. It's easy to get a crooked angle. What I generally do is line up the screenshot in regular mode, then toggle momentarily to flying camera mode just to take the picture, then toggle back out.
Interesting, no? Lots of good resources that are a little difficult to get into decent city sites.
You found 2 horses, but realistically only one of them is available to you for the time being. You better make sure you get it and fast. That should probably be a priority for city #2 and if not city #2 then definitely city #3.
As for how important Iron Working is, I think that's tied largely to how important an early war is. If you want to take out Mehmed or Tokugawa, then you better get yourself some metal, because horses aren't going to cut it for long.
On the other hand, if you're willing to kick back for a while and go after them a little later (but not a lot later!), then you can probably fight off the barbarians adequately with chariots. At some point they'll start coming with spearmen, but until then (anyone know how soon that happens?) you should be fine.
Worst case scenario you could harass Mehmed with horseback units just to keep him under control and then come at him hard with catapults and war elephants. Realistically though, I think you want to get on Iron Working fairly soon.