unless you want to get into building your own fxmap that's probably the best thing to do. if you do want to build your own it's basically the same steps you'd follow to create a voronoi or poisson distribution - there's plenty of code examples online for those
Yes. Check out the Tile Generator node. To get the differing columns, you may need to use two Tile Generators and combine them using a third as the Blend mask. https://www.youtube.com/watch?v=VyFgpitTsYg&t=638s (Jump to 10:38)