doubt you will find information on how to construct games like these. Simply because their actually straight forward enough (real challenge being creating an entertaining ai system which creates a nice mix of wins, loses, attributes to determine team and player success). From ui point of view again thats pretty straight forward, real task is to prioritise presenting alot of data to the user (most important and relevant first, with the option to drill down deeper if they need it, this is typically in the FM series).
As for the scoring system, this should be a reflection of the standard system for 6 nations and rubgy union.
Personally, i think this would make an ideal entry project into games. Could use a number of technologies also for it, flash or silverlight would be awesome, then everyone could play online. Worth getting practise IMO with silver light i reckon its going to take off in next year or so. Nice driving force of MS behind it.