pertaining to squad size;
i'd say 6 is best. it gives you a good amount of dice, (12 on the charge), but the squad should still be compact enough to take as much advantage of any cover as possible... best of all, 6 is an even number so it's perfect for maximising your scoring unit potential! (hey, you never know when your rough riders will surprise you and 3 or 4 will live through it all!
)if you're really paranoid about the horrors of 'rubber lance syndrome', then you can give your veteran sergeant the honorifica for 4 attacks on the charge with his lance! or else if you have the slot to spare, just take a 2nd squad of 6...
you might also want to invest in a power toy for the sergeant. it can be handy once the lance is used to have at least a few attacks that still pose a real threat to heavily armoured troops...
i've played against many players who use both larger, (8-10), and smaller squads of only 5...
- the larger 8-10 man squad is just a huge target. it's not possible to hide them and you can bet that your opponent will make the rough riders a high priority target due to those dreaded hunting lances!
in the end, the squad either runs after they suffer 5 or 6 casulties or else there's so few of them left that they accomplish very little and only kill 2-4 enemies at most...
- the smaller squads really suffer from the attention of the dice gods... with so few attacks, even when the squad is at full strength, there's very little chance that you can break the enemy... once those lances are used up, the rough riders of corse are just as paltry as those fresh conscripts!
cheers!