I use the native Calendar app, which has a 'to-do' list and it two-way synchs to my Outlook Calendar, plus I can see it on Android tab, and outlook.com.
Only downside you cannot make a direct tile to task list but easily accessed from Calendar.
I did a hard reset on a Lumia 920 last night - it took 90 minutes - it was only newly set up so just had a handful of apps, and one 300Mb map file - no idea why it should take that long - but the message is be patient and keep it on power.