50k hp, healing boost depends on how comfortable you are with healing, i healed with ~850 with sacrificial power up and it was okay, i also healed with 1400 and with 1600+ and it doesnt really make much difference for me. I think more than 1000 might be a waste of stats but in the beginning it might cover some of your missed timings Also makes it easy to use sacrificial power all the time, which doesnt use extra mana like benevolence.

There might be more experienced clerics who say you can have even less healing boost but i dont really care about minmaxing in pve, as long as it gets the job done.

If you have chanter with protection spell in your group, 50k hp is enough rest is not important you will be always get carried as support if you have chanter, your duty there is being sidekick to chanter. If you wanna go w/o chanter you need at least 1600+ healing boost and 50k+ hp with decent gear but 1800 is very good if you can do it otherwise you will most likely out of MP to heal group.