Who said healers need restoration staff? :) With templar toolkit you can easily play without resto staff and still have nice big heals for your group.
With this setup you provide up to 4 synergies and typical healer buffs. In execute its possible to hit more than 70k dps.
You can also try different monster sets if you have trouble with staying on melee. Symphony, Stormfist, Magma or Kargaeda are good alternatives.
Food and mundus is up to you. If your group has enough synergies its okay to stay with thief, if you use bi-stat food or group has no synergies Atronach is probably better. You can also replace altar or something else with Channeled focus for magicka recovery or go magicka recovery or magicka reduce cost on your jewellery enchants.