I worked with a guy who worked on IceCube. He flew down to the South Pole, went all the way to the station, just to install debian for their data processing systems. I was... a bit jealous.
IceCube sends housekeeping and priority transient events (like a supernova) over satellite, selected high quality events get synced over satellite daily and everything else gets stored and shipped out in the summer. There is a redundancy everywhere - it’s a very thoughtfully designed system.
As for darkness; consider a single day is stretched out over the year. There’s only a two months of astronomical night and the moon is up every couple weeks. You’re correct though, that the station is isolated between mid Feb and late October.