1.  Can you give me an example of what is meant by the phrase "an Officer must aim to fulfill his orders, although this applies to his command as a whole, with individual bases allowed to be held, for example, as a reserve or to protect a flank."

No problem.  We generally play that an Officer must give at least half of the bases under his command the same orders as he himself has.

For example, a Leader with Attack orders has five bases in his brigade: three armed with melee weapons, two armed primarily with missile weapons. As long as his three melee-armed bases have Attack orders and are attacking, his two missile-armed bases could be given Forward or Hold orders: presumably providing covering fire for the attacks of the other bases. The majority of the bases of the brigade are following orders and attacking.

Note that if the Leader wanted the missile-armed troops to move into melee as well, then their orders would have to be changed to Attack orders, which would take command points.