One key thing to remember is not to stress them out by trying to feed them day after day. Try once a week and if your snake doesn't take your offering, just refreeze it and try again next week. One thing to remember about our lovely pets is that even though they may not show outward signs of stress, they could still be trying to adjust to their surroundings. This is a period of adjustment for both you and your snake. The hissing may just have been your pet feeling things out to see how you would react, who knows? I have a snake that wants to be held everytime I go into my reptile room. When i walk in she comes right over to the front of the viv and raises up and waits for me to take her out. All I have to do is hold my hand next to the top and she climbs right out and wraps herself right around my bicep and lays her head on my shoulder and will stay there all day with no problem. We have just bonded and my wife, who couldn't stand to even touch a snake 3 months ago has bonded with another of our B/P's and she spends alot of time with her.
Remember, your pet has a personality all it's own, just like you do. From the sounds of things, he's just getting adjusted to his new surroundings and getting used to you as well. It sounds like you are off to a great start in establishing a great relationship with your snake and I'm sure you'll enjoy many years of companionship with him.
Oh, before I forget, if you feed frozen/thawed to your snake, I would only refreeze an uneaten rat once. If your snake doesn't take it the 2nd time, I would throw it away and start with a fresh one the following week. Just a suggestion, but that's how I feed mine...
BTW, congrats on your new pet!!!!