K.R.
At 2 1/2 years old, our son was still not sleeping through the night, we switched out his toddler bed for a full sized bed - huge bed for a small boy yes, but we already had the mattress and box spring. Funny thing happened, he slept through the night! Of course, I was still up in the middle of the night going pee because I was pregnant, so when I went to check on him he was always in a different spot on the bed - I guess he just needed room to move!
On the going to sleep alone issue, what I did was a version on was is outlined in "Happiest Toddler on the Block." Sitting on the floor by the bed I would rub his back for about ten minutes, then say "I'm going to go switch the laundry. I'll be back in two minutes." Then I would come back in two minutes (this is important so that (s)he will trust your word each and every night). I would sit and rub his back for another five minutes and say "I have to go start the dishwasher, I'll be back in five minutes." Then I would come back in five minutes! Sit and rub back for two minutes then take a ten minute "break," you get the cycle. He would always fall asleep waiting for me. He wouldn't get out of bed because he KNEW I was coming back. He is now six years old and at night I rub his back for five minutes, then leave and do a five minute "check" and then go fall asleep sitting up next to my two year old! haha Someday my nights will be mine again, and so will yours :)