Let's start with audio. It's very simple: look on the back of your computer. There should be two small jacks to plug in things (like headphone jacks on a portable CD player). One of them has a picture of speaker and is for sound output (if you want stereo sound). The other one has a picture of a microphone and is for sound input. Some computers come with a microphone. If you don't have a compatible microphone, buy one. You can also get 3D audio and external speakers.
Video Input and Video Conferencing is also easy. All you need to do is buy a video camera. Now, most cameras will be color but some might be black and white. Some models you can attach to the ADB port (that's where you keyboard and mouse are attached). Others will attach to a SCSI or USB port (see the difference in SCSI and USB). The camera will come with the software necessary to use it. For Video Conferencing you will also need a high speed modem or other connection.
There are 3 ways to get pictures on your computer. The first is by using a video camera to take a still (see above). This is low quality. The second way is by using a special digital camera. This is very high quality. Digital camera's don't use film, but instead have a "memory pack" which stores the pictures; the more memory the pack has, the more pictures you can take on it. The pictures can then be transfered onto your computer by either hooking the camera up to your computer or by puting the memory pack cartridge into a special external drive on your computer. Digital cameras are very nice but very expensive. If you want to print your own photographs, you will need a special printer.
You can also get pictures onto your Mac using a scanner. There are 3 types of scanners: flatbed, sheet-fed (like a fax machine), and hand held. Hand held scanners are cheap and basicly obsolete. I don't see many sheet-fed scanners in use; flatbeds seem to be the most popular. Sheet-fed has only one advantage over flatbeds: sheet-fed are smaller thus taking up less room. Flatbeds can be very large and occupy a lot of room but they have many advantages. First, sheet-fed only accept thin paper that measures 8.5" x 11" or (maybe) less; flatbeds can accept more sizes, and like a copier, it can handle different thickness'. Also a sheet-fed only scans the item once whereas a multipass flatbed scans it multiple times insuring higher quality. Multipass scanners are more expensive. Size and ability to recognize different color (color depth, measured in bits) also affect cost. Scanners come as either SCSI or USB (see the difference in SCSI and USB). The models can cost as little as $120; models for profesionals cost much more.