Thanks for all the info! The boat has 3 flush-mount rod holders, plus 6 of the Scotty ones mentioned by hvyhaul above, i've used them before and they have been very sturdy, so I likely won't be making any changes regarding rod holders.I'm pretty new and still have a lot to learn, so take this with a grain of salt...
My penny-pinching attitude is to acquire used gear cheaply, and I'll be the first to admit this isn't always the best idea!! My gear is a mish mash of whatever I could get my hands on, and it works once you figure it out, but I'm finding out that some of the stuff that I've got isn't necessarily what I like.
Jos told me that a dipsy rod should have "dipsy" written on it. I've run dipsies off of other stiff "trolling" rods without any problems, so I'm not sure what the concern is. My rule is to make sure the rod is rated for the line. If you're planning on running a spread with 4 dipsies, make sure you get some longer rods for your outside dipsies and shorter rods for your inside dipsies.
A rod suitable for a downrigger should have a ton of flex. You want to be able to bend it in half, so that you can load up tension on your clip. When the clip releases, the rod will spring up and take a bunch of slack out of the line. When I started, I had a downrigger rod spooled up with lead. It looked like a wet noodle pulling 5 colours. It had very little backbone left for fighting a fish. I quickly replaced it with a stiffer rod.
For me, I find that a smooth even drag is very important, and this is what cheap reels lack. Line counters are essential for dipseys, but for me they aren't essential for leadcore or downriggers (nice to have but not essential). Calibrate your line counters for dipseys. If you're looking at used gear, I'd take my old Penn 209's (with no line counter) over my newer cheap gear (with line counter) any day.
The Penn Rival reels are a great value for the money right now. I bought the 30 size, which are great for lead but I'd prefer a smaller reel for my dipsies. Easier to get your hand around them.
You didn't mention rod holders in your post, but it is a very important piece of the puzzle. If you are new to dipsies, they have a ton of pull. Dipsey rods should be near horizontal and held in something metal. Avoid plastic!
That's all I've learned so far.