Restarg (Lestallum) is one of the bigger cities in the game, which has a connection to the summon beast Titan. In Restarg players will be able to check-in to hotels to rest, eat and participate in events; you can also drive around with your car. Some destinations will be accessible only with trains. Int he game if you don't rest or camp, you won't be able to recover from status aliments, and you won't be able to use buffs in battles.
In the game each day is about 1 hour in real time, your party can go for a max of 3 days without rest before their status started to get negatively affected. You can buy food at restaurants or make food at campsites, which gives you buffs; and sleeping will help maintain the buffs longer.
Initially only Noctis can use magic, later in the game other characters can access magic via a special system which hasn't been revealed yet.
Titan will be one of the primary summon beasts, but he won't be in the upcoming Episode Duscae demo, another less story related summon beast will be available instead.