While there certainly aren't "rules" for street photography, there also isn't any shortcuts either. The use of telephoto lenses in the street is generally frowned upon for a couple of reasons. One is that the resulting photographs taken with long lenses just don't seem to be as esthetically pleasing as those taken with normal to wide lenses. Case in point the link you provided. I also didn't care for Struellis work. Telephoto lenses can also result in the kind of negative attention that shy photographs are trying to avoid by using them in the first place.
So stick with wide to normal lenes. I shoot both 35mm and 6x7 film in the streets. I use a 35mm lens for my Nikon F2 and a 50mm and 110mm (wide and standard) with my RZ67. Doing so puts you in the mix of things which is where you want to be when shooting street. If you still find yourself uncomfortable then perhaps street just isn't for you. Nothing wrong with that; street isn't easy and many people try it only to discover it just isn't a good match for them. Good luck and most of all have fun! If it's not fun, it's not worth doing!