Have you taken him to see a vet? Maybe he won't take the dried food because of a problem with his teeth? It was my first thought when you said he sucks on the wet kibble. He may have retained some baby teeth or have another dental problem
It may be that he's just not used to it but it may still be worth while taking him in for a check up
A great way to teach him to quit barking is to first teach him to "speak" or bark on command! Once he grasps this concept you can get him to "speak" then tell him to "HUSH" (use whatever command you feel comfortable with) when he stops make a huge fuss! From then on whenever hes barking unnecessarily you can use this command!
As for him being left alone, I think so long as you can come home to him every lunchtime its not too long at all. Many dogs are left far longer without any problems. I think you are very fortunate to get him at an age when he is maturing and already though the worst of the puppy phase, he may take a little longer to adjust but it sounds as if he has found the perfect home.
Good luck!!!
PS if your'e really worried about him getting lonely you could always get him a fursibling
