So what Apps do I Need to Sync reminders and calendars ? I have an a5 2016 and an iPad Air 2 to be Synced.Apple has got you there....right there where they want you to be!
Expect iMessage and FaceTime ( I hardly use FaceTime and we mostly WhatsApp here in Europe) all my iCloud services work perfectly fine with my Samsung S7 together with my Mac. You just have to know which Android apps (e.g. Calendar and Mail apps) to use.
Love the a5's Build and Design.software could be a bit faster but hey I saved about 380€ compared to an iPhone 6s ( had many issues with the iPhone 6s)