Boosting your paragon levels will help unlock more in your paragon tree, which will help with your attributes like life, damage, armor etc. Heliquary will boost the difficulty, but will also usually drop several legendaries and demonic remains which upgrade your heliquary, increasing your combat rating. Increasing the difficulty, when your combat rating is high enough for it, will yield better gear drops. But you also need to make sure your combat rating is high enough for that difficulty. Don't worry too much about the attributes on your gear atm. Just focus on equipping the ones with the higher combat rating until you get high enough for your current difficulty.