Ok the answers to your questions:
The GL's rivers are generally small, less than 80', and sometimes as small as 20'. There are exceptions, such as the Muskegon, St. Mary's, Niagra, and more that are over 100' wide. The rivers are usually deep and have many pockets that cannot be fished effectively with west coast spey fishing techniques. There is very little room for backcasts on most rivers, and most people resort to single handed rods. I find that a two handed rod works great as you can control your line and keep it on the water longer. You can buy lines to cover your needs, but spey fishing envolves more. Most use a thin diamter, running line and add pencil lead or split shot and drift fish with it on a flyrod setup. I resort to more traditional methods, using a floating line and indicator to nymph, or multiple sinking tips to get down without the use of added weight. The line I explanined is practical. Double Taper lines are great since they can be roll casted, yet if the belly is not on the water than it is hard to turnover your leader. On the other hand, a WF line is great for loading the rod quickly and may be better than a DT at times since you need the line to pick up and reload without having to false cast as often. With this line I explained, you get a 25' head of DT line that butts up to a short headed nymph taper flyline, and are connected by loops. The nymph taper is WF and accelerates the line out with enough power it turns over the lighter DT line, and will allow effecitve presentation of indicators, splitshot, or the use of mini tips to get down. The nymph taper's head is about 30' long, and you have about 25' of DT line, so the overall length is about 55'. The "power hinge" affect is what causes the line to turnover, yet allows proper mending as well.
Hope I cleared this up!