LookInspect the bike for rack mounts. Review I saw stated the bike has rack mounts front and rear. Panniers do effect the ride. If it gets cold or rains and you don't have gear that is not comfortable. I happen to prefer front racks. Get some small waterproof panniers. But a large seat bag may carry what you needsneed. Problem with a frame bag is then you lose water bottles.
Same review said it would take 28 mm tires. I would go with quality 28 mm touring tires.
General tune up. Replace worn parts.