Hello and welcome!
You are asking some good questions and I wish that there was an easy answer for you. But what I have discovered is that all dogs and puppies are different and what works for one doesn't always work for another.
You are right that potty training will be much more difficult if the pup is crated all day. And these dogs do need exercise, so if you are able to, it would be great to take your pup to a doggie day care a couple of times a week and/or see if a neighbor would come in and walk him or play ball with him for a while. You could also hire a dog walker.
An older dog might come with a different set of problems, especially if you get a rescue (since you won't know much about his life before you...) still, most doodles are really good dogs.
Even though they are generally great dogs, many back yard breeders or puppy mills are so careless in selecting parents that you can get some puppies with temperament issues.
Also, dogs will be dogs...and you will have to deal with messes, chewing, digging, etc. So, as long as you are fully prepared for the challenges as well as the pleasure, your puppy will adjust to your schedule and becoeme a loving pet.
Be sure that if you get a puppy, you enroll him into puppy kindergarten classes. They are so much fun for you and your puppy!
Here is a link about crate training and at the end of the article, it tells you how long you can leave a dog in a crate:
http://www.inch.com/~dogs/cratetraining.html
I don't like to dwell on the negative issues, but I feel that it is very important to be realistic when you are making such a huge decision and as much as I adore my dogs, they DO have some negative traits. :wink: So if you are aware and prepared, you will be more able to deal with the issues as they arise.
Select your breeder well, because you will want to ask questions along the way and a good breeder will be there for you!