Traits mostly give the slave a bonus or malus to certain occupations or tasks. Pretty Voice gives a bonus to charm and social jobs. Strong increases strength which is useful in combat. Scarred decreases beauty and charm, so it will decrease the cost of a slave and in an job where looks don't count such Mage Order Assistant can result in getting a useful slave for cheap.
The number of interacts the PC can do is based on their endurance. Increase your endurance and thenumberof potential encounters will increase.
Mostly slaves all like the same things, your attention, gifts and so on. However if a slaves loyalty and obediance are low, you need to stick chating and maybe hand holding. Gradually their obediance and loyal will increase. Alternately, you can beat them until their obediance and fear goes up. The Maid and Butler outfits increase obediance a little at the end of each day.
You can try the sandbox mode instead of the story mode when begining a new game. You will start with more resources and will already be a mage guild member.
At the very beginning, set your first slave to Hunt. They won't be very good at it but usually can feed two people. Go onto town and try to complete a slave guild quest or two. This will give you money, experiance points, mansion upgrade points, and increase your reputation. Check the Mage Guild, completing the initial quest will give you membership and a useful spell.
Don't try to get a bunch of slaves right at the beginning. They will be hard to manage and not bring in much money. Give yourself time to gain a level or two (remember to increase your endurance) and get a cushion of money farming captured bandits and completing slave guild quests.