The most important thing is for the core players to be healthy for the playoffs. Resting Rondo and KG in January doesn't mean anything if they're playing banged up in March and April. Health is the most important thing overall, and if KG and/or Rondo aren't healthy, they shouldn't be playing. Small injuries can turn into bigger injuries if you keep playing.
A great record and HCA is definitely a great thing to have, and makes the road to the finals easier, but this team can win in the playoffs on the road. Winning in the playoffs if they're not healthy?? That's a different story.
That being said, January doesn't look like a particularly hard month. 11 of the games are against teams .500 or worse, and 10 of the games are at home, inlcuding a 6-game homestand.
I don't think Jermaine's minutes should be limited. I think he should consistently be getting more minutes (if he's contributing) to build up his stamina, and with KG most likely at least missing SOME time, he'll have that chance for extended minutes.
In terms of guys like Bradley and Harangody, neither of them have a place on this team in the playoffs, so the importance of their minutes and experience is far down the list.