My son started sleeping through night around 4 5 months
My son didn't sleep through the night til 2 years old. I know how badly it stinks.
As far as potty training goes, my son is not quite old enough for that yet. But at the daycare center I used to work at, we would encourage potty training around 2 years old. We had a 2 and a half year old who we helped potty train. We would make her go potty every 20 min the first few days and then extend the interval as the days go on. Sometimes getting them to go is hard because they argue with you and tell you that they don't have to go. But kids lie sometimes so you can't trust their answer. Just find a way to convice him to go on his own. I had to talk a little girl into going by telling her that if she didn't go potty she would ruin her dress and I'd have to put her in boy clothes until her parents brought her some of her own clothes. That worked for her. Most kids aren't as difficult as she was though haha
I was fortunate. My son was sleeping through the night as soon as I brought him home from the hospital. As far as what can help a baby sleep, it sounds like you're doing everything I've heard to try. Iwould also make sure not to give him anything sweet too close to bedtime. No rough/rowdy/exciting play too close to bedtime either. As it gets closer to bedtime, excitement should wind down. Maybe a night light in the bed room? I'm an advocate of the ignore and let them sooth themselves philosophy (unless of course it actually sounds like something is wrong). Maybe some soothing classical music?