My druid team is currently 75. I'm leveling 1 bear/4 moonkins. Pre Northerend 5 insect swarms would usually kill a regular mob. In instances I usually do MF/IS/SFx3. For regular grinding IS and wrath are ok but starfire gets better mana efficiency. If you're running low on mana in instances I recommend a SF spam instead of wrath as it's more mana efficient. I didn't spec eclipse on the moonkins as it's hard to use the procs efficiently with 4 moonkins when boxing. My tank/feral casts improved fearie fire.

Most of the fights my followers stay in human form as I'm using them for heals. I'm going to try going 1 tree/3 mookins now that I have slightly better gear but my previous attempts were so so. Trees aoe heal is ok but if you're taking a lot of aoe dmg then it's easier for the moonkins to throw lb/rej on themselves and on the tank (this made the first boss easy in nexus compare to nightmare when she would toss you around).

As a side note.. I find my bear tank is way easier to heal than my paly (he currently has around 32% dodge/63% dmg reduction). I tried taking my pally/4 druids to AzjolNerub but he kept getting killed. With my bear I can cast 4 regrowths and that pretty much lasts for the entire pull. With pally I'd have to throw additional rej/lb. This is probably gear related.. at lower levels bears seem to preform better. Less spiky dmg and more health gives you a bigger buffer for heals.