Using Apprentice HD, I realize that I lose nice features like FBX output, but I'm told that via ROP or SOP or something-OP that even with the Apprentice HD version I should be able to export a fluid surface from Houdini into Max.

Recognizing it has to use only features in Houdini Apprentice, can someone point me to a tutorial or list the steps of taking a fluid sim, and outputting it as a mesh to use elsewhere…I'd really like to see how these render in 3dsmax

You should be able to export your mesh as a *.obj file sequence. Note: This will only export the geometry. No materials, lights and such.

Append a file-SOP or a ROP Output driver SOP to your last SOP inside the geometry-container of the fluid. Both will bring you identical results.

For the ROP Output Driver use these settings:
- Valid Frame Range: ‘Render Frame Range’
- Start/End/Inc: first frame number, last frame number, 1
- Output file: $HIP/a existing sub-folder in your project folder/filename.$F4.obj
Now hit ‘Render’.

If you want to use the file sop, do this:
- File Mode: Write files
- Geometry File: $HIP/a existing sub-folder in your project folder/filename.$F4.obj
Now rewind the playhead and press play. Each frame will be recorded to disk.