First let me say, it sounds like Roscoe is very intelligent. And second let me say, that I am no "ME, human, me dominant; you, dog, you submissive" kind of a trainer and then also let me state that I am just an at home, watch your dog and try to think like them and see the world from their point of view kind of a person. I am my dog's caretaker and friend. All of this because I don't feel like I know you.......yet!
Now to your questions:
Being a laid back sheltie is a GOOD thing. Never think that is a bad thing. Shelties can seriously be OCD about most things and one that is laid back is much easier to deal with in the long run. So I think you are ahead of the game there.
The leash problem MUST be solved. For you to care for you pup, as you know, they must walk and accept a leash for safety. We always start with the leash on them day one and them dragging it around to get use to the weight of it. If you haven't done this, start today! Then as the little guy gets more ok with it, pick it up and firmly insist he comes along with you. Some people hold a toy in their left hand that the dog loves or a treat. But gently and firmly insist. It is not an option for him to not walk on a leash. It is his safety. There are tons of tricks and tips on getting them to walk on a leash.
Next you said he stays out of reach when you call him. He is playing with you and pushing your buttons at the same time. IF he is allowed to get away with this "keep away" game of himself, he will continue. If he were mine to train, I would be back to 100% on leash (which yes I know he dislikes) but he would never have the option of not coming to you. Again for safety, recall is vitally important. He must come to you and he must touch you when he does come. I have taught "touch" at the end of a recall command. We do not use treats, but you are probably going to. Put a little tiny piece of hotdog between your middle finger and ring finger and let him remove it as a reward.
About being scared, shetlies are timid and are easily overwhelmed. My McKinley will still not go up my cellar stairs (he's a year). As far as getting out of the crate, don't get into a power struggle pulling him out of there, back to the recall and the the touch command and he will start coming out on his own.
And as far as bonding, first, I didn't catch the age and if he is fully housebroken, but if he is over 6 months and fully housebroken and he should be by that age, then let him sleep at the bottom of your bed. Shelties I think bond better when they sleep with you. If he jumps down in the middle of the night and I really wanted to bond with this pup, I would go and retrieve him and pull him back in bed with me. Shelties love to sleep with their backs up against things and their head hung over things and on "pillows." You will become what he sleeps up against and you will become what he rests his head on.
Train every day for at least 15 minutes and PLAY every day with him. If you want him to go nuts when you arrive home, be nuts when you come home, jump and run and bark at him when you walk through the door, trust me, if you bark at a sheltie to get him to bark, he WILL learn to bark and then you will be wondering why you started the barking game!
I am sorry this was long, but I just felt like you were disappointed in a breed that I absolutely adore. Shelties do care alot about their caretakers, but they take a while to warm up and that is because they are intelligent. They are a breed that you are going to have to win their love and respect, but it can be won and it such a blessing when it is won. Shelties are not for everyone. They have their goofy traits, but what I saw in your thread were all correctable.
Good luck and keep us posted.