I would recommends the Wireless Mighty Mouse by Mac.
It may work with your Desktop. It depends if your PC has the capability to use wireless devices
PC mice commonly have physical scroll wheels and right click buttons. The new Magic Mouse for Mac has them, but they are touch sensitive, as is the entire mouse's surface.
The maximum is however long your cord is, or however long your wireless reaches (if you're using a wireless mouse), you can also use extensions if you want it to go further.
You use two fingers and stroke downward on the mouse pad to scroll down and to go up you stroke upward.
If you MAC is old then it uses a different motherboard than a PC. These days MAC also uses intel processors so in theory you can use the same motherboard as PC but there may be problems in adding the peripherals like MAC's keyboard and mouse to the PC motherboard and vice-versa. It all depends upon what you have got.
MAC/PC/printer to router. Router to modem. Modem to wall/internet. Wired or wireless router is optional, same principle.
Yes.. Search for the modem if wireless, or plug in Ethernet cable and access network settings! Remember, windows is just bill gateses pc version of the Mac os!!!
If her mouse is wireless and your computers are close together, yes. Move computers farther apart.
Yes, I use one on my desktop all the time because I have small hands.
You can use a PC remote to view photos, watch movies and listen to music from your computer. It acts as a wireless mouse, but can control your computer's media software.
You have to start 'Sharing' in System Preferences on your Mac if you want your PC to be able to connect to Mac. Then in XP, go to My Network Places and workgroup and find the shared files on the Mac.
A wireless mouse can be used for both. As for recharging, most wireless mice you will look at take Alkaline batteries, so you have to replace them when they die. If the mouse contains Rechargable batteries, then yes it will have to be plugged into the PC (or wall) to charge.