RaF 1-90

[MiRai]

I plan to start a new 5 box team after the holiday sale. I only have 1 account now with a green geared 90 druid and 90 dk.

Would like to go the LFD route, but only have enough to buy 5 sets of guild heirlooms. Worth it to get full heirlooms for 5? How many hours would that take?

I would say that if you want to use dungeons as your path for leveling throughout RaF, then you will want as many heirlooms as you can get. Speaking from experience, you probably won't need them for the first 70 levels as long as you've got a decent setup, but once you hit Wrath content you will find yourself extremely under-geared and possibly struggling without them (even more so come Cataclysm content).

As for how long it takes to grind out the JP to acquire the ones you want? Well, that depends on how fast you can queue for dungeons at max level since every boss will give you 100 JP. Since they nerfed the Honor > JP conversion (and because random BG victories are so... random), you'll likely not want to use random BGs as a source (although you can purchase PvP heirlooms and probably get away with them for RaF leveling just fine).

I just did a non-stop grind for a full team worth of heirlooms (all upgraded to level 85) and it probably took me 3-4 days to grind out over 70,000 JP as a tank queuing for heroics.

If I boost the 1st group, would I have enough JP for full heirloom sets for 5 then?

You don't start getting JP until level 70 (I think?) and even then you're getting close to zero per boss kill. Cataclysm content yields a little more JP per boss/instance, but I doubt it's enough to sufficiently supply you with heirlooms.

LFD 85-90 better than questing?

It really depends on the person. If you have a kickass group that has tight rotations and is able to kill things efficiently, then it's likely better than questing; but then it comes down to... Are you going to be completely bored with the same few instances over and over again for 5 levels or, will you want to break the repetitive grind with some questing?

For the mathematically challenged peeps like me, can a kind soul post am updated A > B > C type of guide for the new RaF 1 to 85 to have the max # of 85's across all accounts?

RaF was just increased to 85 a few weeks ago and I don't know of a guide like that that exists.