Though i've never met Von in person, we've corresponded through the years.
Von will be one of the perfect instructors for a photographer adding motion imagery to their repertoire.
He began as a fashion photographer, morphed his business into a still - digital tech company and now has experience in motion from the RED to the 5d2 and I assume everything in between.
To add to everything Von mentioned, which is mostly on the technical side, one of the most important differences from stills to motion is the ability to tell a story, whether it is 10 seconds or 97 minutes.
When we do parallel projects in motion and still, even if still imagery has priority, I always start with either an outline and/or storyboard (for mos) and a script if dialog and we shoot the motion sequences first, scrub through them quickly, Identify which style imagery will work in stills, then usually recreate the stills to have continuity.
My suggestion is when you test, shoot a story. It may be as simple as two people walking and holding hands, dodging traffic at a cross walk, laughing, then walking on, but with motion you'll be amazed that once you get into the cutting room, all that footage you thought you had covered probably is only 1/2 of what you really need.
As every editor and director will tell you, you can almost never have enough footage, angles, takes and coverage. An editor is only as good as the imagery provided and if it's a stylistic on trick pony, it gets old fast, if it's just visuals we lose interest quickly, but if it's a good story, regardless of how it's shot we will watch it and remember it.
Also understand that not every production is going to be big budget or in the case of parallel production enough time to really go deep into the storyline. Time on set is the main enemy, budget obviously sets the time on set.
I suggest shooting a story, then editing it yourself, whether it be in i-movie, or all the way up to avid. You'll learn more about shooting and directing once you try to cut something worthwhile than you ever will just learning how to shoot a camera, even if your plans are only to work as a camera operator or dp, because a great dp really is part director, sometimes the dp is the director.
I also strongly suggest taking one of Dov Simens' classes. http://www.dovsimensfilmschool.com/
You'll learn more about how hollywood really works than you will working in hollywood for 5 years. Dov pulls no punches and gives it out straight. If you can't take the class I think Dov sells dvd's or tapes.
Now when it comes to cameras I'll say it again I love the RED, but a lot of cameras in the right hands can do amazing things, even the 5d2. In regards to shooting vertical, I've personally done some of that in testing but never been asked to do it on a paying gig.
Most video for web will be in 16x9 format, some 2 to 1, but video or motion or cinema has no real standards, regardless of who you talk to. There are as many formats for the screen (any screen) as their are workflows, editorial systems, color correction suites and even file types with different codecs (compression/decompression).
Ask 4 editors or color houses what they want and you'll get 4 different answers.
Our studios work mostly in house will dedicated people, so we are in a closed loop system. Even with that our system is in the process or changing.
Just remember there is no exactly right camera, right style, right way of working other than this. With motion you must plan ahead, be very, very exacting and cover more than you'll ever think you need.
P.S. if you want to see the best interactive magazine for the i-pad type of delivery I suggested subscribing to GQ. You'll see vertical ads become horizontal and every type of interaction imaginable. GQ has it down and is a great place to open you mind to what is coming.
P.S.2 One thing about a still photographer adding motion imagery to their services is it's not mandatory, it's an elective and without a business model it will be like setting up a facebook account for no reasons other than everyone else is doing it. It may get you attention, it may be fun, but at the end of the day you can spend you life doing something that doesn't move your business forward. Business model first . . . then start looking at cameras, screens, editors, etc. etc.
Motion imagery is like most "new" things, especially in technology. At first it's over hyped, then later it's under estimated until it levels out and just becomes another standard of our industry.
I think all of us should understand that advertising and editorial is changing. Prior to the web most media was a monologue, but with the web and it's thousands of forums, replies to the editors, facebooks, twitter, etc., the communication industry is learning how to merge content from monologue to dialog successfully.
So, in summary unless you have a burning desire to shoot motion imagery, a passion to tell a great story and a way to profit from it, stick with what you know until the industry settles down.
Once again IMO.