Hi again Phantoma, to answer your questions...no the segmented front rollers do not make it easier to turn....that is the job of the split rear roller....in fact
all Scotties (domestic and industrial) have a one piece front roller, with the exception of the (badge engineered) Morrison mower from New Zealand (almost a direct copy of the Victa Imperial)
To your second question, you will find the 17" Model 45 Scotty/Rover quite suitable for your size lawn, but of course, a 20" Model 45 would mow it a trifle quicker. I have found that my 17" Scotty is a very versatile machine having recently used it commercially as a favour to a friend.