Yes, it will take a pc monitor with the mini's adapter plug which should be provided with the unit. Any key board and mouse with a usb style plug. I BELIEVE that Apple will no longer support the operating system, leopard and the unit itself does not have the capacity to be upgraded.
Unfortunately no. Doing iOS development requires the developer to have the the latest Mac OSX, if not the latest then only one behind. This model of Mac mini can't run mountain lion or Mavericks. So it is unable to download and install the latest version of Xcode, Apple's IDE. Currently mine is used only to surf the internet and watch videos. It is seven years old and not much runs well on it.
The speaker is a thin band all along the bottom edge of the Mini. It's adequate -- I'm listening to music right now -- and works best if the Mini is positioned on its side so that the speaker isn't facing into the desk.
Upon receipt of my Mac Mini, I immediately hooked it to our Panasonic 32" HDTV. It's a CRT, about 3 years old, with a DVI input. The picture is fuzzy, by computer monitor standards, but usable if all you want to do is watch video. In fact, video quality (using QuickTime) is quite good. Most of the videos I watch are Divx, with a resolution of 624x352, or better. They look about as good as DVDs. And QT gives an easy way to make them fill the screen. I copied the Front Row remote commands to my universal remote, allowing me to pause/play and forward/reverse the program without touching a mouse. So far, the computer has been flawless. It hasn't yet been connected to a real computer monitor. Also, I bought a large external HD and that's where I keep all the videos.