You nailed it when you said it's "like they're in a clique and you're on the outside." As both a stepchild and a stepmom, I know exactly what you're talking about. There really is a bond there that you have no part in. And that's not a bad thing; it's just a "thing" thing.
My dad and I have always had a close bond. For one thing, we're cut from the same cloth, for another, we had 10 years of history (which was my whole life) before my stepmom came on the scene. It made it hard, as a stepkid, to not exclude her from our inside jokes and nonverbal communication. My stepmom didn't handle it well, and now that I'm an adult, I see her side better than I did as a kid. Children are selfish; that's one of the things that makes them different than adults :)
As for "liking" your stepson, you don't have to. Loving someone is a choice we make, but liking is a lot more to do with similar personalities and common interests, of which, it sounds like you and your stepson have few. So don't beat yourself up over that.
On practical advice, the first thing I'd do in your shoes, and this is entirely my opinion so feel free to take or leave LOL, is to set out some ground rules. Tell your stepson that it is important to you that, as a family, you go to church on Sundays and that everyone is up, dressed and ready at X hour. Insist that he get up and get ready, even if you have stand knocking on his door for 10 minutes to drag him out of bed. Learning to go to bed in time to get adequate rest is part of growing up, and he'll eventually get the message. At least, in theory.. LOL
My oldest son (my step) is one of those people who never stops talking. After a lot of experimenting, we have started to use the word "rattling" to describe his incessant chatter when it gets out of hand. For example:
"Blahblahblahblah..."
"J, you're rattling. I would like to enjoy this show. At the commercial, I'll be glad to hear what you have to say." And then I ignore him until the commercial. It took a few weeks of counting slowly to myself to keep from screaming at him while he kept going, but it did eventually start to work. The key is to really listen at the time I said I would. By knowing he WOULD be able to be heard, he got less demanding about it. I realize it's hard to be patient when the topic is not something you care in the least about, but patience is a virtue, or so I'm told ;) There are times now when I can actually say, and I try to say it calmly, "honestly, I don't have the patience/energy/time/interest to listen to this tonight. May we talk tomorrow, so I can watch this show?" Again, the key is follow-up. The next day, I have to set aside a few minutes to go find him and say "I'm ready to listen, if you'd like to tell me what you were saying last night. Or is there something else you'd like to talk to me about?" I often do this when I'm getting ready to fix supper, do dishes or fold laundry. He talks nonstop, so he doesn't expect a reply, and I have something to occupy my hands (and brain) enough to keep from going insane :)
Learning to listen to him taught me a lot about loving him. As I developed more patience with him, my attitude towards him changed. At first, I was very reserved with him. Now it's easier to love him like my own, because he's become my own in those times I spend letting him rattle at me. On his weekends with his mom, I've come to miss his chatter when I'm fixing supper or doing the dishes! I don't care a bit about his video games or the movie he watched at his mom's last week, but I enjoy his pleasure in having an audience.
As far as his dad's involvement, I don't know very well how to help you. After single parenting for 6 years, my husband was relieved to simply drop the bulk of the parenting on me. When I make a parenting decision, he basically just lets it stand.
Try talking to him without accusing, at a time when you're not actively upset. Tell him exactly what you wrote here about your concerns for your baby. Tell him the stress is getting to you, and you don't want it to interfere with being the best wife and mother you can be, and then ask if he has any ideas for solutions.
Balancing parenting more than one kid is tough, whether they're your stepkids, your own kids, or a mix of both! If the 17 year old were your biological child, you could have STILL written the same post. Your husband may be concerned about him getting ready to leave home, and so, want to "spoil" him a bit before he heads off into the big, cruel world. He may just figure "boys will be boys" and therefore not see which behaviors are problems. It may also be that your husband figures he'll have "time with the baby" when the older boy has moved on in life, not realizing it doesn't exactly work that way. A family counselor who specializes in step-family integration may be needed to sort it all out, and that'd be SOOOO worth the time and money invested, if it helps bring harmony to your home.
Try to see your son as a part of you husband when praying for patience. Which traits does he have that are "just like Dad?" Does he have any in common with the baby? If you can see him through the filter of someone you love deeply, it'll be easier to love him because of that connection.
You can also try to enlist your stepson's help with some of this. Ask him what time he thinks he needs to shut down the games in order to get up at X time in the morning. Let it be his choice, but insist on the wake-up, no matter what. (Note, did his dad WANT the games in his bedroom so he'd stay out of his hair while playing them, and so your husband wouldn't have to see/listen to them?)
I'll be praying for you. ANY 17 year old is a trial; you're certainly not alone on that! And blending families, even under the best circumstances, is never easy. But when has anything worthwhile ever been easy?!
Good luck and God bless!