I picked up a Purifier spec with some points in Sentinel (I think?). Healing is alright but I need to make some mouse over macro's or else find an addon similar to grid + clique. I did 2-3 T1 dungeons, got some gear upgrades, I felt like had the dungeons on lock down. Started the whole planar attunement thingamajig.
Purifier/Sentinel would probably be a very familiar build for you. As you've probably already figured out, it's a bit of holy pally (heal bombs), a bit of disc priest (shields) and a bit of resto-shammy (AoE heals). Warden builds are also pretty common for 5-mans, but you have to watch out for threat issues with tanks if you load them with HoTs prior to the pull.
Farming planarite & other such currencies, should I just plop myself into zones and do rifts, I saw people advertising raid rift pugs, is there a set gear level I would want to be at? What is the best way to go about it?
With your background, I'd say that you could probably jump into oversized raid rift groups now and do just fine. Raid rifts are tuned under the assumption that they're going to be done by an adequately geared raid group of 10 people, but there are no penalties or restrictions for doing them with larger groups. ****, you might even be able to hold your own in a 10-man group.
As far as earning the planarite and other goodies, zone events are the big sources of those kinds of things, followed by farming rifts in Shimmersand and Stillmoor. Raid rifts are about essences and Inscribed Sourcestones but the planarite is pretty poor for time invested. If you can fall in with a pack of players during a zone event and just cruise around obliterating rifts/invasions/colossi, that's where the planarite starts to add up, and Trion recently made it so that you can earn quite a significant amount of Inscribed Sourcestones from them as well. (I tend to get 5-6 of them if I get in at the start of a zone event.) I think that if your focus is going to be raiding, one of the first things you might
want to get is the Omen Sight (25000 planarite). I think
you need that to enter slivers, but maybe someone else can confirm. A lot of the other abilities you get with planarite are nice to have, but not 'need to have' kinds of things for a raider.
If you've got your full sigil (the one that allows you to equip 2 greater and 4 lesser essences) and you've mapped out what lesser/greater essences you want to fill it, it's easier to plot a course of action to get them. You're back at a good time, however, since there's a world event going on that will typically result in an increased frequency of zone events, as well as an increase in the number of players out doing rifts and such for the world event dailies.
If you can find yourself a solid raiding guild, there are also a bunch of recently added crafted gear options that will help accelerate your gearing curve and get you into Hammerknell a little quicker, but they're expensive to make right now so a helpful guild would be an asset. You really do want the zippy land mount and between that and training various souls to their top ranks, you'll be strapped for plat for a little while.