1 http://www.newvegasnexus.com/downloads/file.php?id=38623, incase of extra dungeons, see http://www.newvegasnexus.com/downloads/file.php?id=38719
2 http://www.newvegasnexus.com/downloads/file.php?id=37871/http://www.newvegasnexus.com/downloads/file.php?id=34759 i think have tweaks for those.
3 http://www.newvegasnexus.com/downloads/file.php?id=40340, or http://www.gamesas.com/index.php?/topic/1143482-wipzbeta-darnified-ui-nv/page__hl__darnui with tweaked settings for the Hud hiding. If "X" means keyboard button, you can just remap action button (by default "e") to x from control options.
4 http://fallout.wikia.com/wiki/Ratslayer, scoped Hunting rifle or Anti-Materiel Rifle that are already in game? Haven't seen any good modded ones yet.