What is an Apple Push Notification service?

Hi I've been receiving emails from Apple which look legit but don't make any sense. They say "The following Apple Push Notification Service certificates, created for AppleID [my ID] will expire on May 18, 2017. You can renew your certificates with your Mac server administration tools"

What is this? I don't have a Mac. I have a PC and Laptop with Windows and an iPhone. I do have an iCloud account - is that what they are referring to - and does this message mean anything I need to attend to?

Issue with Iphone and Itunes Syncing and uploading photos?

I was first trying to upload some of my photos & videos by syncing them onto my iPhone 6s, and I've been having issues can anyone help me fix this problem including how to get rid of the error message and able to put my folders with my images on my iPhone?

Error Message: The iPhone _____ could not be synced because the sync session failed to finish

Can does your phone still update while it's off?

I'm getting iOS 10.3.2 on my iPhone 5c. It just 1 hour remaining. I'm not waiting that long! I can't just keep clicking my phone for an hour so it won't turn off. Can it update while it's off?

Are we making enough?

Dad makes 85k before taxes. Mom doesn't work. 3 kids, one 16 one 13 and one 4. My dad already payed off his 70k college debt in 6 years, and his car. Are we making enough to afford things such as a vacation, a new iPhone every year, a new car etc?

Is iPhones better with boost Mobile or metro PCS?

I currently have a ZTE pro from metro PC s I want a iPhone but everybody say get a iPhone from boost Mobile because the service is better. But my sister says service from metro is better. What do you guys think?