First, welcome to APUG, from across the Georgia Strait.
I'm going to make a slightly radical suggestion. Keep your eyes open for some studio strobes (monolights) that are cheap (really cheap) and used. They won't satisfy any long term needs, but if you have plans to experiment and familiarize yourself first, $200 spent on Craigslist might teach you a whole bunch about what you really need.
If you then decide to buy a new setup, make sure you get something mainstream. The cheaper knockoffs are generally poor value.
I'm happy with a single cord to one light, with the others triggered by optical slaves. Optical slaves don't work well, however, on location if there are others present taking photos (think weddings).
Ebay has thousands of cheap radio triggers. Most people I've talked to have been reasonably happy with the results they have obtained from them. They are, however, a bit less dependable than something like a Pocket Wizard, and don't offer the wiz-bang extra features for interface with and control from the latest model digital cameras that the top of the line Pocket Wizards have.
If you buy older, used flashes, they may have a high trigger voltage. That can damage newer electronic cameras (both digital and film) and radio triggers not designed for high voltages. I have a set of very old Bowens monolights that have very high trigger voltages - I won't connect them to anything other than mechanical cameras, or older optical slaves. A Wein "Safe-Synch" would be another option.
A 6x4.5 back for your Mamiya RB67 would give you a 50% increase in the number of test shots per roll when you are learning to use your lights.
A good flash meter is a must, and the ability to trigger the flash from the meter (by cord or otherwise) is a valuable feature.
The modeling lights in strobes definitely vary in quality. Placement relative to the position of the flash tubes is critical when using direct flash.
A separate digital camera can be an okay substitute for a Polaroid. A digital back would be better (same camera position and lens) but the cost is, of course, unrealistic.
A separate digital camera is less accurate as a replacement for a flash meter.
If you can swing it, a visit to either Beau Photo in Vancouver (good knowledge and some rental selection) or Glazer's in Seattle (great knowledge and rental and sales display selection) could really help you in your choices. There are also a couple of places in Vancouver that rent equipped studios.
Hope this helps.