My little boy is left handed, hes coming up to 7 and has had major problems with writing, connected or not I don't know but imo it is!He also struggled with reading but now reads really well. Hes never really wrote his letters backwards apart from 'p,d,and b' which I think is normal, I remember doing it myself as a child! He does however do alot with his right hand, actually he does everything with his right hand apart from write! He also kicks with his right foot. He has terrible troubles with his balance and co ordination which again may or may not be linked.
My little brother is 11 and he is also left handed, he struggles with writing and balance and co ordination, more so than my son does. BUT he is amazingly clever, his school work is way beyond 'the norm'. He spells better than anyone in our family including my mum! He spells words I cant even say! He was reading and doing sums at the age of 3!
The one thing I have noticed is that they are both very clumsy!