They have bearings made of nylon or teflon which allows it to move in altitu de or azimuth very smoothly. The greatest quality of the Dobsonian mount is that it is very inexpensive, works well and it can even be made easily at home. Standard altazimuth mounts are used mostly on refractors. They work like the Dobsonian mount but they are much less stable. They are on top of a tripod which reduces their stability.
Telescopes usually come with eyepieces.
The wider the barrel the better. The last thing to look for in a telescope is the finderscope. Refractor finders look like small refaractors that have crosshairs in them to help find objects. These types of finders work very well. They can show you objects that are invisible to the naked eye.