You have some good heroes, but i would focus on getting more. Always remember to save gems and spend them when there will be Treasure Mining event aiming to get silver chest, which is usually around 7-9k gems, but this is not fixed. You can spend less to get it, but also will have to spend more. This way you will also receive Event Hero Card which will give You chance to get Fox. I think Fox SS were also reward from Line Defense but i am not sure now.
Getting Zephy is not that easy, cause You will have to use Tapjoy and finish good offer during Accumulation Pack which have Zephy as reward.
As for Heroes most interesting ones are:
Dove with TP/Survival, Forest Ward and Balloon pet usually,
Lazu with Revive10/Revitalize, Holy Conviction
Occultist with TP/SL, Holy Conviction
Rambard with TP(again)/SL, HC
Vailant Saintess i am not sure about build here, but i would aim on SL/WA, Malaise
Phobos with DC/Revite(Empower), HC
Landwalker with SL/Empower (also don't know good build now), HC
Sasquatah with defensive talents, HC
PD with Empower/Regenerate/SL (pick 2), Healing Ritual.
You don't have WallaWalla therefore Ghoulem must be current healer with def talents also, but if You have more Water Priestess copies you can evolve and use her instead.
Epic heroes are not Double evolved therefore using them is limited.