im in yr 12 an i agree that yr 11 is hard only because of the amount of work and the differnce in the load from yr 10. i think the most important thing is to make a routine...heard it before it really works...get urself into a routine of study even if it is not kept exact everyday itstill helps...
the answer to ur second question is that yes 3u dose scale heps better then 2u and if u get lower in the 3u exam than all ur toher subjects the scaling will make up for it so u dont need to worry about it....2u scales really good to but if u can do 3u by all means do it....if i go bad it wont...