Noob questions about refreshing squads

[Maxtax]

Also, if you play one game in a day do you think it's better to do training for the rest of the day or to play a friendly?

Friendly for me and then training for fine adjustments to be close to 99 condition untill the next game.
In general manage well your resources be patient and avoid doing large changes in your team, the concept of the game and the reason for playing it, as far as i am concerned, is to simulate "managing"