You can search the approximate level of NMs on YG. I would guess that the easiest are Nest Commander, Queen Bolete, and Slippery Sykes.

I haven't tried to solo any NMs since the changes in patch 1.18. It's much more difficult to solo anything now. But in terms of what level you need to be to solo NMs, I would imagine that it depends on which class you're going to play. If you're using a DoW, you're probably going to need to be at least level 45 in one class, and hopefully have several cross class abilities (like Second Wind from Pug, Bloodbath from Marauder, Cure from Conj, Sacrifice from Thm, etc.). It's probably a bit easier to solo if you're using a DoM class.

As for where to post, you might be able to get more info on the New Player forums. The more experienced players in there seem to be searching those forums solely to help other players, if they can. So they tend to be very helpful indeed.