Dodge, I can't say for certain, but knowing MARX I would strongly guess it is the same type of smoke generator in both units. One of the things that kept MARX going was streamlining of parts, which of course is a cost-cutting practice. Did you check out that web site I posted the links to? That site will help you out tremendously with all sorts of ideas. There are layout plans and some have 3D illustrations.
As far as your track and the engine slowing, this is normal and typical. This can and will happen regardless of track type. Most folks, once they decide on a permanent layout use what are called feeder wires. In other words, you have two wires attached to the same posts coming off the transformer going to the same rail: you don't want one wire from one transformer post going to the center rail and the other on the same post going to the outside rail. The dual wires off one transformer post need to go to the same rail.
You place a lockon on one side of the layout and another on the furthest point away from the transformer, and this will help with the loco slowing down when it gets on the far side of your layout. It is natural for the loco to slow some when going around tight 027 curves.
Concerning your track, it is probably well used having been pulled apart and together many times. This can weaken the crimps on the ties of any kind of tubular track. Plus it can loosen the track pins and enlarge the holes on the other side of each track piece opposite the side with the pins.
Once you decide on a layout design you like (see the thortrains site for good track plan ideas), then you would use some pliers to gently crimp the open rails (opposite the track pins) a little tighter. It'll take a little more elbow grease to push the sections together, but it will help greatly with electricity flow in the track.
Also, if your track pins are dirty or corroded, these need to be cleaned or replaced. Another hint for your track. Before you do your permanent layout, spray a rag with WD40 and wipe down the rail surfaces. Let this set overnight or for a day or two depending how good your track looks. Then wipe it down real good with a clean cloth. The WD40 will help inhibit rust and put a protective coating on the track. I've done this with old used track with good results.
In addition to the thortrains site, our host magazine, Classic Toy Trains has done some good layout building articles in the past few years. The most recent issues had a feature on building a "retro" style layout with tubular track like yours. There was another feature on a logging type layout using Lionel FasTrack in the past year, and another article a year or so ago on building an "and and over" layout using 027 track. If you can find these back issues, they'll help you out. Plus there are some Kalmbach paperbound books on building a beginners layout... these will answer many questions and give you ideas.*
For example, you can also use a hollow core door to build an easy and portable layout, You can also use construction insulation foam core board for a layout instead of plywood. There's all sorts of different approaches, all with different pros and cons.
EARL, those Seuthe units just aren't very good in my opinion. Bachmann makes a good smoke generator for around $6 (if the price hasn't gone up) which I've had a bunch for years. They're reliable and great, but I use them in buildings. They're square and I don't know how well you could get one into a locomotive... I've thought about it myself. I also have a Model Power smoke unit (which looks similar to a Seuthe unit) in a K-Line diner building. It's been there for years and works far better than any Seuthe unit did for me.
I've read where some guys have removed the Seuthe unit and sprayed WD40 inside it, let that set, drained it and then powered it up with low current to burn off the WD40. I guess the WD40 helps to clear up any gunk that has accumulated on the sensitive center pipe in the Seuthe unit. I've never tried this one, but again, I've read this in other places.
*This was an unpaid endorsement, though Bob Keller, you are always welcome to send me a train car. I prefer the starter sort, so it won't set you back a fortune! I like the Lackawanna Woodside Reefer in the recent Lionel starter car offerings... hint hint. I won't hold my breath. 