No Iona doesn't stop that. In your case Iona only stops you from casting red spells, but what your doing is just putting a creature card from your hand into play with Hunting Grounds triggered ability and not actually casting them.
Just a note, if Gaddock Teeg is on the battlefield you can't even suspend a non-creature card if it's converted mana cost is 4 or greater. By rule you have to be able to begin to cast the spell from your hand to suspend a card.
You would get the +3/+3 and the triggered ability since the triggered ability is part of the equipment. However you would lose first strike since the equipment is granting that ability to the creature it's attached to.
2) Her ability will trigger even though she is also going to the graveyard.
Actually this is incorrect. If you look at glissa it states that her ability triggers when a creature is put into a graveyard. Since Wrath of god puts all creatures in the graveyard at the same time her ability wouldn't trigger until she's in the graveyard (at which point the object no longer has that ability). This is different then if the card stated that "as a creature leaves the battlefield then <triggered ability>". If that was how it was stated then it would trigger for each creature leaving.
Edit:
I stand corrected...
Note - As long as you have Threshold.
Yeah I just reviewed the rules. I was thinking when it's put into the graveyard from anywhere. I stand corrected...
Actually this is incorrect. If you look at glissa it states that her ability triggers when a creature is put into a graveyard. Since Wrath of god puts all creatures in the graveyard at the same time her ability wouldn't trigger until she's in the graveyard (at which point the object no longer has that ability). This is different then if the card stated that "as a creature leaves the battlefield then <triggered ability>". If that was how it was stated then it would trigger for each creature leaving.