Re composition and tripod, I often hunt for composition freehand, once I found a shot I like, then I get the tripod out. I find with tripod you get even cleaner compositions as you can really examine the shot, without having to worry about holding position. Obviously, what you do works for you. Just my 2c. I learned a lot about examining the camera image from 4x5" [upside down and backwards]. It slows you down but for the better.
I am with you re getting the shot right in camera. You get different looks when using ND grads or doing HDR or heavy RAW adjustments. Occasionally, filters just don't work, and you have to do some processing. Had a rock hole with a light beam through the middle and was shooting 4x5". Did a 3 frame exposure series, then scanned chromes at 500 MB a pop, then sandwiched the three layers with free rotation, then HDRed the aligned frames. Computer was rather challenged.
Don't know about free HDR software, I use PS CS5.5 for pretty much all my imaging needs, except z-stacking (ZereneStacker).
Good luck with your photo job. I'm doing just some stock on the side, but am not happy where things are going. Rather doing low volume private sales than getting ripped off by agency. Again, my 2c. The best approach thus far has been writing photo articles. That actually pays pretty well. Fortunately, my day job take care of the camera expenses. Over the years I've had a bunch of macro lenses. First one was an OM Zuiko 50 mm, then got the OM 90 mm (gorgeous!), also the 80 mm bellows head lens (1:2 - 2:1) with the sliding extension tube (genius design, still miss it), Micronikkor 105, Pentax 100 mm for underwater, Zeiss 100 mm CY, Zeiss 100 mm ZE, Canon MPE 65, and Canon 180 mm is on the way. Also have a Rodenstock 180 mm Apo-Macro-Sironar for 4x5" [ArcaSwiss], which is about a 60 mm equivalent on 35 mm. For >7x I move to stereomicroscope. Did some wide angle reversed on bellows with OM and Contax in the past, but did not get a bellows for the digiSLR anymore. Lens stacking is another approach. Back in Contax times, I stacked a 50 mm 1.4 on a 100 mm macro. It vignetted at infinity on the 100, but at closer focus it worked better. Now with the MPE 65, there is no need for stacking anymore.
Re focusing screens, check out
http://www.focusingscreen.com, or Beatie (
Beattie Intenscreen Bright Focusing Screens), or
KatzEye™ Optics - Custom Focusing Screens. There may be others. If you are more old school, then get one with split image and microprism ring. AF still works with most. Not sure which body you have. I have a Haoda in mine, but Haoda does not seem to exist anymore. LiveView with 5 or 10x works quite well, indeed.