No. Different iMacs require different types of memory modules. Most major Mac-friendly RAM vendors should be able to recommend the correct RAM for your model iMac. Please see links below for more details.
A new iMac comes with 4GB of Ram installed. You can add more at any time.
It does everything any other computer will do.
It runs on the OSx operating system. It would not be an iMac if it ran on Windows or any other system.
Sure, just copy them to a CD or Flash Drive.
There are apps that will only work with Mac OS X which can be on any Mac computer - iMac, MacBook, Mac Mini etc.
Yes. DeSmuME does.
The main physical difference between 128MB and 256MB of RAM is the amount of memory chips present on the module. A 128MB RAM module will have fewer memory chips compared to a 256MB RAM module, resulting in the difference in capacity. These memory chips are responsible for storing the data and allowing the computer to access and use it when needed.
You're computer will require a "DDR2 SDRAM DIMM". DDR2 SDRAM is the type of memory you are after, it is also a DIMM. Most modern memory are all DIMM's (Dual inline memory module), much older ram were SIMMS (single ingline memory module). DIMM refers more to the physical make up of the module (DIMMS have contacts on both sides of the module). So any DDR2 SDRAM that you buy IS a dimm. You may want to look at the wikipedia page about DDR2 SDRAM at http://en.wikipedia.org/wiki/DDR2_SDRAM
The same thing any other computer was used for.
Yes, but you may need an adaptor.
Turn it on by pushing the power button on the back left bottom of the iMac.
Yes, 3 broadband can work on an Apple iMac as long as the iMac is compatible with the type of connection provided by 3, such as a Wi-Fi network or a USB modem. To use a mobile broadband connection, you may need to install any required software for the modem or configure the network settings on your iMac. Additionally, ensure that your iMac's operating system is up to date for optimal compatibility.