Yep, just smoke a small butt and it will take care of itself. Of course, the more you smoke, the more seasoning occurs (some like to call it "patina"). In any case, the smoke and fat will plate out on the interior of your smoker. Most folks leave it alone until it gets really built up and needs to be scraped. I wipe down the interior with a damp rag after every (or almost every) smoke just to get the softer fat out before it solidifies. I also cover the bottom with HD foil ( be sure to punch a hole for the drip pan), and also cover the shield over the wood box with foil. Just my personal rule, but I always clean any part (the cooking grids) that comes into contact with raw meat, every time.
With CS electrics, preheating is just not necessary. The smoker comes up to temp in under 30 minutes, no matter what you put in it. I'm not sure about your SM025, but my SM066 starts at full heat and stays there until the set temp is reached, then begins to regulate (there will be some overshoot, but not much). For a cook that takes several hours, 30 minutes isn't much and you have the safety and convenience of loading a cold smoker, even in the winter. Many chefs will tell you preheating any oven is only necessary when you are baking pastry.
Hope this helps - again, good luck and enjoy.