Hi Shervin,
Canon makes an application called "EOS Remote". I believe it's available in both iOS (iPhone) and Andoid versions. The app connects to the camera via WiFi and is able to transfer images and also remotely control the camera (remote shooting). You can find numerous videos hosted at YouTube demonstrating how the app works.
I noticed you also asked about the "STM" mark on some Canon lenses. Canon lenses have three different major groups of motor technologies and the "STM" mark indicates that the lens uses Canon's new "STepper Motor" technology.
The most basic lenses use motors which are neither particularly fast nor quiet. When shooting video it's ideal to be quiet so that the noise of the motors isn't picked up by the microphone. When shooting sports or action it's nice to have motors that have snappy focus performance and can track action without lagging behind.
Canon's STM lenses are much faster than the standard motors and almost completely silent. Some are so quiet that the internal micorphone cannot pick up the sound at all. Some of them do have sound which is barely detectable. This is quite a performance step up from the standard motors -- especially for video shooters.
Canon's USM lenses have the fatest forcus performance and are also extremely quiet, but as they are noticeably faster than the STM motors, they are not completely silent (but they come close). For action photography, lenses with USM motors are ideal. For video, usually a less snappy focus transition from one subject to another is preferred so it's not so jarring to the viewer. On the 70D for example, you can be recording two subjects at different distances. You can focus to one subject by touching your finger to the LCD screen... when you're ready to focus to the next subject, touch your finger to that subject on the LCD screen and you'll get a smooth focus transition direct from one to the other (no focus hunt) but not quite so fast as to be jarring.
As for your question about shutter speeds... I was actually referring to the frame rate. E.g. one camera might be able to take 3 shots per second... another might shoot 6 shots per second... another 8. The 7D can shoot 8 shots per second. The 70D comes in a close 2nd place at 7 shots per second. When you're shooting action photography, it's nice to be able to put the camera into "continuous" mode and blast off a full second worth of shots. When you inspect them later, you'll find that often one of them stands above the rest and will be glad you captured a group of shots and not just a single shot. It's often all about that "decisive moment".
You can control the actual shutter speed on these cameras as well... you can take shots from as slow as a full 30 seconds to as brief as 1/4000th of a second and some cameras go to 1/8000th of a second. When shooting action, you can typically "freeze" most action at speeds of around 1/500th of a second or faster... but sometimes even 1/250th of a second is brief enough to freeze action. You can create images which "imply motion" even though it's a still image, but showing motion blur in the image. To do this you deliberately set a slower than normal shutter speed.
When you're shooting in particularly low light... far lower than a camera could normally handle, remember that there's practically no such thing as "not enough light" as long as your subject is not moving AND your camera is not moving. E.g. put the camera on a steady mount (such as a tripod... but some people rest a camera on a bean bag, etc. -- just so you can be sure the camera isn't going to move) and shoot the still subject... you can hold the shutter open as long as necessary to get the shot (these cameras do have a "bulb" mode... this involves using a remove "wired" shutter release (because just touching the camera to press the shutter button will shake the camera enough to spoil the shot) and put the camera in a mode which holds the shutter open as long as you keep holding the button pressed on the wired remote (the wired remote is an accessory... not included... but these are inexpensive.)
Some of this is a bit advanced and as you are admitting to be new, you'll want to learn the basics of exposure. There are a couple of good books that tend to be recommended over and over. One is the Bryan Peterson book called "Understanding Exposure". The other is the Scott Kelby Digital Photography series... this is actually a four volume set but it gets good reviews from beginners. Both authors try to write in a style that does not assume you already know the lingo as they explain the concepts.
A DSLR is a bit like owning a fine musical instrument. One can do amazing things with a Steinway piano... assuming one actually KNOWS how to play the piano. If you don't learn, even the best instrument will not improve your results.
Cameras are not nearly as complicated... there are just a handful of basics and then you can get amazingly creative with them -- but if you leave the camera in auto-mode you'll hardly tap the potential of what it can really do for you.
Tim Campbell
5D III, 5D IV, 60Da
