You don't need friends OR a guild to be able to get cata games and heal. Catacombs are always looking for healers and its the best way to level if you don't have too much eff gees invested in your char.
Stats: Intelligence!
As for gear, you don't need to spend much at all at the low levels. 1fg an item and you can still do really well. If you're looking to solo it, go for an int. robe and staff with a charm of your choice with some EE on it.
If you decide to try out healing in catas, you can go for some heal mastery on your items and EE on your heal charm.
Can go into specifics, but really, trying things out and seeing what works will really do you wonders!