Hi
Contacts:
You should be able to export contacts to a .vcf file using your win8 phone. Transfer the file to your S7 via the sdcard or using a PC or dropbox, drive etc and import the contacts file you saved using the settings within the contacts app. There is an app (paid) called PhoneSwappr on playstore that automates this using cloud storage.
Apps:
Windows apps are not going to work on an android phone. Its a totally different operating system. There may be some apps/games that store data in cloud services which can be transferred to the android version of the same app, but this is not common. There may be some developers who will let you have the android version of their app at little cost if you have already purchased the wp8 version - you need to ask them (nicely)