Personally i would put a couple more points into cha for the channel (at least 12) I would probably lose a couple points from int and con for str (for when you need to smite the foes) Then take toughness if you really want the hp. I'm a fan of both, scribe scroll is awesome for a cleric..oh where is dex? One thing i always have a tough time deciding on is if it is worth taking that lvl of fighter for the heavy armor and additional combat feat. I would also go travel +10speed is nothing to sneeze about
Depending on how much fighting you wish to do, I'd suggest the Crusader archetype and stat out like this:
Str 14
Dex 10
Con 14
Int 8
Wis 16 (14+2)
Cha 14
and take the Travel domain (you only get 1).
-- david
edit: and consider variant channeling, disease. saves on spells.
Alrighty, let's see.
I think you might be overthinking it a bit.
DM papa has the right idea on stats, though I'd take Intelligence down to 7 since it's functionally the same for you in that regard as 8 and nets you two more points to toss into Dex for a total of 12 meaning you can easily think about combat reflexes as a second feat for human.
Heavy armor proficiency is just fine and I'd take Travel with it since a 30ft movement speed in heavy armor is pretty nifty.
Weapon wise I'd seriously consider the Longspear/Cestus combo and taking combat reflexes. This grants you a surprising amount of area to cover with a two handed weapon and when combined wiht your mobility and heavy armor make you a rather formidable combatant in the early game.
By third level I'd grab scribe scroll. I wont spoiler details about RotRL but I will say it may come out invaluable to you if you consider and plan ahead what you want to do. Fifth level is where power attack can start to get good for you since you'll have access to some fairly significant buffs.
As for general strategy? Early on just bless, divine favor, whatever else you want to do and take your time to slowly move into melee combat. Squishy is relative as you and the summoner alone can handle most of the encounters by yourselves.
Check out the Varisian Pilgrim from Inner Sea Magic. it's an archetype that really fits the Desnan cleric, and lets you use domain abilities on your traveling companions. it does trade out medium armor and shields for this, but you can gain that back with a multiclass if you wish.
the Spherewalker prestige class is another good option for increasing your versatility, though you'll need to talk with your DM about it to ensure you can meet the entry requirements. Having played through RotRL, I can think of several places that would count as Holy to Desna, and there is sufficient distance traveled to make it possible.
I had a blast with a half-orc inquisitor of Desna in Serpent's Skull, which might be a better option for combat medic than pure cleric if you want some more oomph. Judgements are limited in times per day, but early on it makes up for being a 3/4 BAB class, and once you can toss bane on your attacks it's icing.