try putting him in his crate for short periods of time throughout the day while you are home and walking around. he will cry and scream and want out desperately BUT don't let him out until he calms down. once he calms down let him out. Put something good in the crate for him like some toys or some treats. make going into the crate a positive experience for him. When you let him out of the crate don't make a big fuss. Act like its no big deal he was in the crate and its no big deal that he is out and you are home. most likely he will be happy to see you but wait until he calms down after getting out and then praise him. This will condition him to think that you leaving is not such a horrible thing. After all you will come back to get him
you are doing a great job with the potty training by the sounds of it. keep it up. When he does mess on the floor just take him right outside immediately. make sure to clean it good. I know some others in here have some good recommendations for a good cleanser. I can't remember what it is called lol
As for keeping him up. during the day let him sleep but when teddy was a puppy and he would start settling down and getting really sleepy at night we would keep him awake. we would pet him and pick him up and try to play with him and he just wanted to sleep so much but this defiantely help him sleep all the way through the night.
Good luck with your new pup and can't wait to see pictures