Yes, the juicer attachments can go in the dishwasher, but unless you are running it straight after using it then I don't think a dishwasher could be expected to remove dried on bits of orange pith etc. The bowl where the juice collects is fine to do in the dishwasher though. The worst bit to clean is the round centrifugal thing that you use for juicing apples and other hard fruit - a spatula came with mine that is helpful, but it never feels 100%.
As for the texture of the juice, it totally depends on what you have put in. You are asking the right person, as this week I finally made my first ever smoothie (Dr Gillian has a lot to answer for....) and learned that the main thing about a smoothie is that the whole fruit goes in, whereas a juicer removes the fibrous stuff. So to make a smoothie you don't necessarily have to use a juicer - a blender/food processor is better. But if you wanted to make a smoothie that contained, say apple and banana and peach, then you might juice the apple and add it to the banana and (peeled) peach that you chuck in the blender. I am sticking to softer fruits in the blender, hard ones in the juicer. With a smoothie you might also add some yoghurt, or milk, and ice cubes, which you wouldn't put in a blender.
Was that as clear as mud? I've just looked in a book I bought this week for inspiration to see if it makes it any clearer. It says
"Smoothies can be made in a blender simply by chopping the fruit, removing skin and pips and blending it all to a pulp. Additional ingredients can be added (they mention spices, chocolate etc). In this way the whole fruit can be consumed, fibre, juice and all. Juicing however, is the extraction of the juice from a fruit or vegetable, leaving behind the fruit's fibre and pulp in the juicer. Almost all fruit and veg are suitable for juicing."
HTH