Hi Rachey,
So sorry to hear what your friend has been through, it sounds horrendous, and what a horrible position to be in, where you have the choice of your babies future, i hope they're coping alright. (which is a stupid thing to say, of course they're not)
As for periods, they can come anytime after the loss, and different doctors offer different advise on how long to wait. The simple answer is, whenever they feel ready to try again, i shouldn't think there is a major time to wait. Having never given birth I would not know a definite answer medically, if she had any complications etc during the birth that might make a difference. But i personally would wait until at least one normal period has passed, that way you know your system is flushed out and everything is in working order.
As for support groups, the only support group I know of is SANDS they deal with stillbirth and neonatal death, they may have some useful advise or at least information on where your friend can find more information, heres the link:
SANDS
Hope that this helps.
There are a couple of others on here who have lost their babies around that time in pregnancy, who may be on later this evening and will be able to give you more advice.
Congrats on your pregnancy buy the way, hope its going well.