Some things I think I do believe about baby sleep

I feel like I've read a lot about babies sleeping and "sleep training," but I must admit my resources are limited. I tend to be the kind of person who believes everything I read or if a doctor said it, it must be true, so I try to do more critical thinking than that. I've especially tried lately to figure out what actually works and what I think I see/experience and what the kids are telling me. Anyway, here are a few things I think I do believe in...

Sleep Routine/Transition Time- It does make sense that they need to settle into sleep and to know it is time to sleep. And, especially with a kid like Rayne who absorbs everything and is hyper sensitive, they need time to let go of the day. She seems to do a lot better when we've taken the time to brush her teeth and hair, read books, talk about the day, say prayers, etc. I think she needs the time with me. I think she needs the calming and shifting gears.

Sleep associations- At first this idea seemed kinda crazy to me, until I read something that explained it better. I can put Caius to sleep in my arms, move him to his crib, he kind of wakes up, rolls over and goes back to sleep. So why in the world would he wake up later and be confused about where he was? Or be looking for whatever he went to sleep with? But perhaps that is true.
More importantly, what I've learned about this, is it's the way they go to sleep that's important. I'm sure I have "taught" him (I might argue that he has taught me!) that he can only go to sleep by nursing and snuggling up to Mama. So, when he wakes in the night, hungry or not, he's convinced he has to have that in order to go back to sleep. Let me say it more nicely, in terms I feel are more accurate. When he wakes in the night, hungry or not, he doesn't know how to go to sleep without it.
We worked so hard through December to break that habit. Then everyone got sick. And then, this last week has been especially necessary to just get him back to sleep the fastest, simplest, happiest way possible. So, we've reverted back to feeding him every couple hours at night! Aye! It's difficult no matter what!
What I'm not sure of is that it's not a problem getting him to sleep. The problem is keeping him sleeping at night. Would it really help to get him "putting himself to sleep?" As part of our efforts in December, he did go to sleep on his own... well, as much as this Mama can leave my baby alone. I would put him in his crib and sit with him, pat his back etc, to get him to sleep. So, probably he was still looking for me when he woke up- his new "sleep association"- and that's why it didn't make any difference to how well he slept???

Sleep cycles- They say babies start establishing more adult like sleep cycles around four months old. That's why he was such a good sleeper and then, BAM, no more. We supposedly all wake up throughout the night, but we have learned to put ourselves back to sleep without really waking. However, we do check our comfort levels then- roll over, adjust the pillow or blanket, etc. So, when baby goes to sleep in your arms and then wakes up alone, it's like he's lost his blanket and can't find it. We're back to sleep associations here. Sleep cycles just explains why they wake up so frequently. And, perhaps, I can buy into thinking that they need to learn to self soothe and put themselves back to sleep.
What I can't buy into is leaving them alone to do this! Every method I've read eventually has you leaving baby alone to figure it our for himself. Even the gentle, "no-cry" methods. With Rayne, at 15-18 months, it finally worked. I put her in her bed, rubbed her back and sang to her etc until she went to sleep and like magic she started sleeping through the night up to 50% of the time. Now, at 2 1/2, she still sleeps through the night only about half the time and I worry she's still looking for me, needing Mama in order to go back to sleep. Did I permanently scar her by not leaving her alone??? And is this really something Caius needs to learn on his own? Because it doesn't seem to work for me to try to help him through it. Perhaps I have not been consistent enough? Or perhaps I have not left him alone enough?
Perhaps when it comes down to it, I just don't want to NOT hold my baby and rock him to sleep etc. Isn't that okay? Can't we do that AND teach him to sleep through the night???