Resto Druid is currently considered the best healer in 10-man. Depending on how good he is, you will have to optimize your build and rotation. You have two options which I will try to summarize here.
Stat Priority: 2 mastery > 1 int > 1 master > 1 haste > 1 crit > 1 spirit
Two mastery is better than 1 int. So for gems you want to do mastery/int for red, mastery for yellow, and for blue you want to use mastery for single socket gear and mastery/spirit for multi-socket gear.
Your reforging priority is mastery > haste > crit > spirit. You basically want to reforge completely out of spirit. I have gone as low as 8.2k spirit using selfless healer build (using heroic Horidon trinket + resto shaman mana tide).
Your standard rotation is Ju - HR - HS - LoD.
I suggest for normal you go with this build. The rotation is very easy and there is not a lot that can go wrong. Also, mana is generally not an issue.
Stat Priority: 2 haste >>>> 1 int > Spirit to comfort > 1 haste > 1 mastery > 1 crit.
Same rule of thumb for gemming. Haste/intel in red, haste in yellow, haste in single socket blue item, and haste/spirit in multi-socket blue item.
Reforging is trickier. At certain casting haste values, EF will give you extra ticks. You get 13 ticks with 25% haste, 14 with 35%, 15 with 45%, 16 with 55%, 17 with 65%, etc. People generally go for the 35% or 45% break points. Assuming you get haste buff in raid, you need 7,170 haste and 10,867 haste to reach the break points, respectively. With the amp trinket you will need less. For example, when I reforged to 10,867 haste, with 2/2 upgraded amp trinket + haste buff, I ended up with 48% haste.
How much spirit do you need? Depends. What trinkets are you using? How many shamans and priests are in your raid? As a rule of thumb, I would start with 11k spirit for 35% break point and 16k spirit for 45% break point.
Your reforging priority would be Haste to BP > Spirit to Comfort > Mastery > Crit.
Optimal rotation: HR - HR - HS -EF
Non-optimal rotation (less mana intensive): HS - HR - HS - EF or HR - HS - EF
Some observations for EF build:
Do not use Crusader Strike to gain HoPo!!! It is a waste of mana and GCD.
Once you have your 4 pc., macro AW and Divine Favor together. The haste buff will give two additional ticks to EF. It’s a massive healing burst.
EF works great with the legendary cloak. With SH build the cloak proc usually accounts for 2 - 3% of my effective heal. With EF the proc accounts for 7 - 10% of my effective heal. The healing cloak proc with EF is on par with the DPS cloak proc.