To get Modo’s selection:
Map this to Left Mouse: Ray Cast Select
Map Lasso Select to Right Mouse
Map Select Through Border* to Middle Mouse: Heavypoly config
*You’ll want to go into the code and change every line of ‘bpy.ops.view3d.select_box’ to ‘bpy.ops.view3d.select_lasso’
I haven’t tested this setup exactly, but it should work.
As far as keymaps go, I highly recommend going in and taking a look at what everything is. There’s a lot to customize, and especially when you get more add-ons, you’ll want to be familiar to best customize to your needs. But it’s important to know that there is a hierarchy. 3D View will override Object and Mesh. This is a good thread to look through, rawalanche is doing a great job, and is taking the time to explain their reasoning as well.
The context menus are nice, but there are some tools that work in all three modes, but will only show up in one menu. You could add them to the Quick menu, but I personally made my own menus with Pie Menu Editor. Pie menus in Blender are great! Much more can be done with them here than in Modo.