Sniffing quickly in sleep? Other sleep oddities?

I know babies do a lot of funny things in their sleep... so couple questions:

Anyone else’s baby have little bouts of sniffing inward rapidly? Just like 3-4 really fast sniffs and then resuming calm sleep? He doesn’t seem distressed, just seems odd as it’ll happen regularly while he’s sleeping. I tried Googling and couldn’t find anything... and it doesn’t sound like periodic breathing.

Also, when does the eye rolling and smiling during sleep stop?? It’s adorable, but I also thought it ends at a certain age?