What to do with my labrador

Like the other poster mentioned, you will have to look a bit harder for a place to stay. Many apartments have weight restrictions on dogs. Labs are considered a friendly breed, so that will make it easier. Some people rent independent houses or townhomes.
Average vet cost in my area (yours may be less):
Office visit fee: $65 (usually once a year)
Preventives (heartworm and flea and tick medicine): $20 monthly
Vaccines: $24 each, mine usually get 3 shots yearly
Wellness check: blood, urine, stool test: $100
So the routine charges are not much, but if your dog becomes sick or develops a chronic condition, or needs to go to the emergency vet it can add up.
Food should not cost more than $50 per month, treats and toys depends on what you want to spend.
If you are all going on vacation and there is no one available to care for the dog, you may need to board the dog in a kennel. That fee can range anywhere from $25-50 per day depending on the facility.