Hi Corey, thanks for your post, and for your interest in our products!  It sounds like you're about to embark on a major project, which is awesome.

To answer your question about our lamp posts, you don't necessarily need to buy them from us, but the advantage of doing so is that we pre-drill the posts (which takes a lot of time to make sure you don't melt the plastic, etc.) and pre-mount the LEDs.  If you have access to a small drill, you can certainly drill the posts yourself.  Then you would need to solder the Pico LEDs manually.  If you're comfortable drilling and soldering, it is definitely doable.  Another lower-cost option is to run the wires down the outside of the post along the back.

Yes, it is possible to control everything from a single point.  Our lamp posts come with 24" cables, so depending on how close each post was to the next, you could connect up to eight of them together using our BRANCH11 expansion adapter, then use our 24" connecting cables to run back to a "master" BRANCH11 adapter, which would then connect to our pushbutton switch, and then to power.  When you add building illumination, you'd need to run a second power line that was not controlled by the pushbutton switch.  Some customers have decided to add multiple switches, one for different buildings or sections, while others prefer to have their building lights "always on".

I hope this information is helpful.  Please let me know if there is any additional help we can provide!

24 LF is an impressive build - photos?  I'm envious with my teeny 4x8 township, but of how we (my 8-year-old engineer and I) built it out...

A single USB power supply off a "brick" for the buildings and streetlights.  I'm away from the photos, but I just did a ~8 brick high stack of round bricks with a clear head and dish on top and stuffed a pico light in there, and as those are 12-inch leads tie together with pico adapters that 'branch' off the building interior lighting.  (I use the 2-light strips inside - bright and easier.)

I've more or less zig-zagged the city blocks to help manage the power load, which has worked reasonably well.  All told, I think I've got about 30 bulbs in 'the grid' today, and it'll grow when a few more modulars are released (I have open space for just three more 32x32 and two 32x16 buildings).

Each of my city blocks has at least one open adapter port for expansion, so we can just jump off without having to up-end the entire thing.  (Unlike some I've seen on Instagram, we remove our buildings from the base plate in town, vs. placing between street plates, so it's kind of permanent-like).  

The only exception is our gigantic Green Gables Stadium build, which has 16 pico lights in the floodlights alone; that will end up running on a separate power supply and switch.  (On both switches -- sorry Rob, I'm cheap at times ;) -- I bought a few in-line USB switches on eBay.  Not as classy as the BrickStuff switches, but they do the trick.

My go-to parts initially were the starter packs: you get a darn good value for what's in there, including the power supply, and it's enough to get up and going... and from there, I figured out where I had gaps, and ordered from there.