to be completely honest with you I have never had to pre heal demon wall before bee's spawn, the fairy is more than fast enough to cover any damage even without being placed ( which I do not do in that fight as it doesn't make since). with the gear you mentioned you should be fine going straight DPS and letting Eos or Selene heal the party, no one should take any heavy dmg ( they should be dodging the floor AOE) Murder holes will do minimal dmg as long as party is dodging, your fairy can heal easily solo even in base job gear!
but any advice here can be used just depends on your style of play, I my self do not place in DW and go straight DPS, if I see the wall wont fall before or close to bee spawn I go full heal and rotate succor on party and psy spam on tank with lus to cover anyone's big mistakes!
and lastly above all else your best friend should you have a bad party in DW is leeches (if you don't remove de-buffs it will make healing that much harder)
