Labs are wonderful house pets!! They do need a lot of activity and exercise however so if you are planning to look into a smaller place then I would also search out where the dog parks are and where you can walk or run him at least twice a day. Figure out if your schedule is able to handle two 1 hour or at the very least 2 half hour slots to exercise him. If you feel that you can manage this then there is no reason that you cannot continue with the adoption.
This depends on the individual dog. Training is very important starting at a very young age. I would highly suggest crate training. By the time a lab reaches the age of 2 years you will know if they can be trusted alone in the home. This is the age when they start to mature. Some however can take till they are 5 or more. It all depends on him and the training that you have done with him. My lab ate walls if left alone for long periods when he was younger. By the time he was 3 he no longer needed a crate and could be trusted. The crate can be his retreat or his comfort zone if you will. This is a necessity especially if you are going to be away for a long time. He can manage to hold his urine by the time he is one year of age for 8 hours. I do not recommend longer however at times my guy held his for 10. The main issue is that he be exercised twice daily. Once before you leave and then when you come home.