the term turbo isnt used in the same sense here! it is actually fundamental impossible to turbo charge 2-stroke engines, rc 2-strokers use high % nitromethane, which will give you all the power you would ever need with no lag
Turbo plugs seal with the button head in such a way you are guaranteed a flush fit with the combustion chamber, which intern gives better performance. the down side with turbo type head buttons is the ability to get a good air tight seal with dirt and crap that can come between the to contacting surfaces. standard type plugs have a copper washer that help get a good seal when the surface of the head button is less than clean.
hence why on-road use turbo heads and off-road use standard heads.
pic comparing the 2 types below...
with regards to inlet port numbers some engines tend to have extra boost and transfer ports which make it possible to direct the fresh mixture into every part of cylinder forcing out spent gas, this will actually give it a better volumetric efficiency (can cram more mixture into the cylinder).
remember more ports isn't alway better! a poorly designed 5 port sleeve may be out performed by a well designed 3 port.