personal preference mate...
depends what youve learnt with.. personally i prefer switch (step in bindings) but the boots can be heavy so it depends how much your planning on walking
the newer switch boots/binding however are MINT they are a lot lighter than the older style and much more secure (doesnt put as much pressure on the bottom of your legs as there is more support in the binding.
As for the size of the board again its personal preference really howevever as a general guide most people have a board which when stood up comes between their chin and nose (ooo er )
the best deals are undoubtedly from america and if you go for a burton board you wont go far wrong to be honest.
CheeRS
Phil