To expand on Steven's answer, you can create some object groups for your different sets of lights (select lights to group then hit shift-G, then hit “x” key to turn on group list with your cursor in the network).
Now you can use @light_group_name as the list of lights to use. The “@” means group.
As for learning houdini, there are some videos around the web. There are also some nice tutorials. The best way is to get your basic skills up with Houdini then get a job with a shop that uses Houdini. Nothing like learning from an existing user. There is also Side Effects support but you need to purchase some Houdini software to tap in to that. There once was an entire Demo directory that shipped with houdini with many examples of specific operators but no longer ships with houdini due to maintenance issues and the large number of hip files.
There is also this forum.
Mainly Houdini is used in mid to large size facilities mainly in the SFX side of things. It is also used as a pipeline solution. It is also used in broadcast shops but mainly Feature Film production is where Houdini is used. Excluding ILM, Houdini is actually used quite a bit on Feature Films in LA and the UK plus elsewhere in the world where Feature Films need SFX stuff.