Get SmartSwitch for PC/Mac. Use that to transfer data from iPhone.
As for apps, you just download the ones you want I guess. You can always setup the phone as you like. Personally as soon as I get a new device, the apps I download first are:
1. Swiftkey
2. Nova Launcher (+Prime and Tesla plugins).
3. ChompSMS/Textra
4. Viber
5. Tasker
6. GSAM Battery Monitor
7. OneNote
8. Bookari
As for help. You may experience trouble with sending pictures. I would assume you know the basics of iMessage. Essentially it uses Apple Servers to be able to send media. Hence it isn't compressed as much. But the app also handles SMS. However the default SMS app in Androids doesn't have a web server to upload media to. Hence they use MMS which on compression destroys the video quality and recipients get a blurry image. The closest things to iMessage on Android is Hangouts and Facebook Messenger. Both work the same way as iMessage, wherein they can handle SMS, but on sending media like pictures or videos, they send it via an online server hence minimal conversion is experienced. However, since Apple servers are closed, Apple recipients need to have either Hangouts or Messenger installed because iMessage cannot receive median from these apps. Hangouts is actually the closest thing to iMessage for Android. The only thing is that it never really caught on for people to use it as their default SMS app just like how Apple users set iMessage as their default app.