Haha as a guy turning 30 as well this year I would also like to know this.. I saw winter festival and Oktoberfest last year but apart from that and maybe taking some lessons at the neighbourhood centre I'm not sure.
I don't think church is a good place to meet singles or is it?
I know there are a few social activities like the play theatre, meditation groups and like you said running and hiking groups.
There is a local board game shop (Afternoonified) and internet cafe (Internet Tea House and one other in the arcade) I guess if you are into that.
There is a Hotel Blue that has nice live music every now and then mainly jazz as far as I know near where the old Katoomba RSL was if you like food and classy music.
Can't say for sure because I was married when I lived in the area. There are lots of cool cafes, some theatre groups. You could definitely join a hiking group or or community group of some sort but I don't know what the single population is like there. There seem to be quite a lot of 'down and out' under 25 singles but then there are also retirees, wealthier older types and lots of tourists. So, fairly diverse. On another note, there are lots of festivals in the area...maybe a way to get involved and meet people? More obviously, there are pubs too. I know you didn't ask 'how' to meet people. I can't really answer your question regarding what it's like to be single there but, there are definitely a lot of things in Katoomba for singles to do! You could also branch out further for social life too...Penrith (not the mountains) is about 40 minutes from Katoomba and it a thriving metropolis. I wouldn't recommend living there if you love the mountain views and small town feel but it could be good for socialising on the weekend! Good luck!