I took a look at your work and see some very fine documentary images. In all honesty I think you have very good potential. You have an excellent sense of what is important and not trivial garbage and your composition and technical execution is excellent. Your subject matter is timely and not a bunch of trivial fluff like much of what I see today.
If you are interested in making a living at documentary photography it will be hard. I can't even support myself fully with the documentary end. I'm a commercial photographer and have been since college. In college I worked as a PJ and was chief photographer the photo for my college publications. I made serious money doing this and was able to take a year off after school and apprentice in a commercial studio under a master and learn the business and improve my skills. I did this and worked 44 hours a week with no pay. This was one of the best investment i could have made. It's paid me back many times over 37 years.
I've done documentary work since the beginning of my photographic interest and done it as enjoyment mainly. I say a need to preserve our culture because it's constantly changing. Only in the past few years have I tried to market my documentary images. I'm entering portfolio competitions, working with a very good writer and submitting applications for grants and seeking exhibitions in museums and galleries. So far so good with the exception of grant money. I've had very good success with getting published internationally such as the current B&W (US) portfolio edition and had excellent success getting my work into galleries and museums. I made the right connections through some of my commercial clients and have a major museum show opening next year in October and a book being published. The museum is seeking funding for the project that will total around $150K. The show will actually be made up of one large show of 70 images and one of 35 that will tour the US museums. I'm currently in another museum show opening this week and have a gallery in Atlanta that is carrying my documentary and x-ray work (
www.x-rayarts.com). All of this is tough to get and takes a good bit of time, persistence and money. A killer portfolio is essential and the drive to get people to look at it. You can't be shy.
I can see the day when the documentary work will bring in good money but it hasn't arrived. My x-ray art brings in very good money with 7 and soon to be 8 galleries in the east and two publishers, one in the US and one in the UK, that have licensed images for murals, wall covering and fine art prints. My commercial work pays the bills and has been very good for 37 years. Simply put this doesn't happen over night and requires 18 hour days to make it and keep it happening. IMO it's worth it just form the satisfaction it brings but the money isn't bad either.
Now the advice. If you want to go into assignment work like a PJ or commercial shooter then DIGITAL is the ONLY way to go. Many established commercial guys went out of business when digital came in thinking they could just use film. It just will not happen except in very rare cases and with a few established pros. Here you need a very good DSLR (no M8, it's a joke in the commercial world). Select a kit for the work you want to do. For example a D300 Nikon or 5D Canon with 3 zooms to cover from very wide to medium tele. You might need a micro in some cases but not all. For ardhitectural you need a full frame sensor and a couple of tilt shift lenses. I find my 24 TSE on my Canon 1DsII to be superb for architectural work. I also find the 90 TSE to be invaluable in the studio for product work. Your kit really depends on your needs. You'll aldo need a good laptop for clients to review images on location (extremely important). Also you need a computer to edit your images and a color calibrating system for your monitor (critically important). A good printer is essential also.
Digital is the key in the commercial world because of the immediate feedback for both you and your client and the ultra short deadlines. Even with film everything in the commercial world must go to a digital file for reproduction. Direct digital cuts out one additional expense for scans and for time. Film and processing are expensive and adds to the cost of any job. In todays world that's important and can be a deal breaker on an assignment.
For documentary work your kit is what ever works for your style. I still shoot 8x10 film all the way down to 35mm. I only shoot film in my documentary work, no digital. Museums and archives want and sometimes require film due to longevity and storage plus there will always be a means of making images form film. I use RF's (Leicas and Zeiss), Nikon and Canon slr's, Hasselblads, Fuji 6x9 and 6x17 and view cameras including 4x5, 5x7 and 8x10. Fit the camera to your needs and subject.
Get savvy on business and keep books. Stay up with taxes and don't go into debt to do this. As a freelancer you never know when your next check will arrive. Have money to fall back on and an alternate source of income (job). I wouldn't hurt to work another job while doing the documentary work because film and printing is expensive.
I hope I've answered your questions but if not feel free to PM.
Good luck! Nice work, honest.