Welcome back! We've missed you.
First up, everything Blue said.
Second, you should also check out Bricklink
if you haven't already. This is a person-to-person LEGO part buying site. You can find pretty much any part ever made there.
Also, you mention looking at MOCs on YouTube videos. You should also check out Brickshelf
, free LEGO image sharing sites, and Flickr
, a general image sharing site that lots of AFOLs use (warning, two days ago Flickr underwent a big change in format and business model, so there are a lot of people ranting about the change right now). Those can give you a lot of additional inspiration. Is your daughter into Friends sets? You might also want to check out FriendsBricks
On local LEGO offerings in southern California, Blue listed the major west coast conventions. LUGOLA is the Los Angeles based LEGO Users Group. I think all of their discussion happens on their Yahoo group
(they also have a website
and Flickr group
, but those seem to be dormant). I lived in LA ten years ago, and at least at that time the LUG meetings were very informal, often at a public setting, and kids were welcome. You should also check out SandLUG
, both of which spun off from LUGOLA over the years. There were a couple of LEGO train groups as well, if you're into train building.
Of course you're also close to Legoland California, and occasionally there are AFOL events held there - in particular they have a Star Wars Days celebration at some point in the year and a bunch of AFOLs always put on a big display. That would be a great place to meet local AFOLs. I think Ace, one of the admins over at FBTB, lives in Orange County, and is always involved in organizing that display. As to other local LEGO venues, there are ten LEGO brand stores listed in California, including the LEGO Imagination Center in Downtown Disney. These often feature displays by local AFOLs, and there are regular in-store events where you might meet local AFOLs. I live on the east coast now, and I'm an hour away from a LEGO store, but when I do get over there I know the local LUG has a set of fliers by the cash register, so you mgiht find contact information in that sort of location.
There are lots of ways to build rock formations. Perhaps the easiest is to base them around BURPs and LURPs (Big/Large Ugly Rock Pile/Piece):
The downfall of that is that they can look repetitive - here's an example of a cliff I made using them:
Here's an alternative, that was all basic bricks (mostly 2x4):
Again, not, IMO, ideal (I'm using my own MOCs so I can feel free to insult them). As Blue notes, many people have moved to a more slope-based rock style, as it looks more realistic. I think Steve DeCraemer gets credit for popularizing this style. E.g. one by me:
The build liability there is that it can be very parts-intensive. (You might also note that over the years I've personally moved from doing a mix of grays to doing rocks in one main shade, I just personally think it looks much better.)
If you're building up your interior with Duplo, one 2x4 System brick fits over two Duplo studs. So you could basically build 2x2 Duplo columns, and then top them with 4x4 System LEGO, and then connect your System layer over top of that.