A little bit of searching and i came up with this:
http://files.halomods.com/viewtopic.php ... hlight=hud
That should help you with removing the hud.
As for walking on walls, open up HMT. Open the map you want to have walk on walls/no fall damage. Click on [bipd] Biped, and select characters/cyborg/cyborg. In the top right of the HMT window you'll see a box labled 'Flags' with two checkboxes. Check them and you're all set.