Record of Agarest War is now out! Go buy it!
Download the user manual here.
There is no "right" answer. Every choice changes the path you'll take, but none of them are "wrong", and none of them will cause you to "fail".
The hints presented in these strategy sections often refer to just one of several paths you can take at any one point.
Each generation will have a number of special events. Be sure to keep a close eye on the Link Gauge and your Affection.
The world map will show your total turns for the generation, and total turns for the entire game. This turn counter advances by one every time you complete a battle--it has nothing to do with the turns you take in battle.
Being slow is...bad.
If you are trying to get as many special events as you can, it's a good idea to save near the end of each generation, so that you can go back and a choose a different heroine if you want to. It's also smart to save at the beginning of each generation, and before making important choices.
It's important to save the game before the generation changes, especially before a certain event that occurs near the end of each generation.
(The Affection and Link Gauge are relatively easy to influence during this event.)
This way, if you miss certain events that you'd really prefer not to miss, it will be easier to go back and adjust the Affection and Link Gauge to get the result you want.
These events don't affect the story of the game, however, and there are alternative ways to obtain gallery images, so it's still okay to skip them if you don't care to go to the trouble.
Something to keep in mind if you are attempting to keep your Affection levels balanced is that it is easier to balance Affection when you choose an option that upsets a character who likes you more and pleases a character who likes you less.
Of course, you can play the game however you want, and you might not want to balance your Affection. There may be situations where you'd rather increase the Affection of someone who already likes you and decrease the Affection of someone who already doesn't like you.