Maiden Voyage on Lake Erie?

I plan on making my first trip to the big pond this summer in search of some walleye & possibly steelhead or lake trout.  I'm a little nervous as to what to expect, since I have only fished smaller inland lakes & rivers.  I graduated last year from a 16 ft aluminum boat w/a 9.9 to a "new" (1995) Ranger 690VS (Fiberglass, semi-deep-v) boat with a (2003) Merc XR-6 150 hp on the back.  Additionally I have installed a (2008) Mercury 9.9 Pro-Kicker to cover my trolling needs.  I am comfortable manuevering and handling the boat on inland waters, but I realize Lake Erie is a whole different world.  Since my vessel would would be considered very small by Great Lakes standards, I was wondering if anyone who fishes out a similar sized rig on Lake Erie could offer me some pointers as far as safely navigating the lake?
Additionally, what accessories would be considered minimal for setting out a good spread (for walleyes).  I plan on fishing at most 3 people, so eventually I would like to be able to run a 6-rod set-up without too much grief.  Right now I have 2 Cabelas Line Counter Rod/Reels for dipsey divers, and 2 Cabela's Planer board rods/reels.  I have a small assortment of Dipsey Divers and have been using the in-line style boards.  Would it be advantageous to add two down riggers on the back, or would I be better off without them for starting out?  Also, does anyone fish with a lead core line set-up, and would that possibly be a better alternative than the downriggers?  I want to keep it as simple as possible while learning all the ins & outs of big-water trolling.  I appreciate any help you guys have to offer me!  Thanks...        
    

That is a decent set up for Erie, especially if you want to fish for bass some.  Go with what you got and buy more as you find you need it.  No need to break the bank on stuff before you really find out if you even like big water trolling.

Deetz , I have a 16' starcraft 85" wide. 

When you run 4 rods as you mentioned, how do you keep from tangling?

I have thought of this setup, but have been afraid of making a mess of my lines.

How far back are the inner and outer rods?

Thanks.

Sixers, run 1 large and 1 med dipsy on the inside rods that way you are at different distances for the same depth, then set the outsides perpindicular and on 3.5.  Still tangles sometimes, but you will get used to it.

Usually small #0 dipsys , jet divers #10-40 , moderate diving lures 15-30ft down out off your planer boards will out fish riggers this time of year ; until they start holding deep . Now fish should be found 20-30 ft deep in around 30-40 FOW until end of June depending on water temps. Get the lures out away from the boat . Know where your lures are running & keep em just below the bait fish you mark. Let the great migration begin Erie is 60 degrees off of Erie ! You hopefully won't need the riggers until July .Tight lines to all.... DC