Well, I've got few ideas what you can improve:
-add item_large_box_mrounds under the info_player_start, so player will have bullets from the start
-replace textures that are
on the list here (stone/stonewall029X for plaster/plasterwall036X and others)
-You can use music on the map as .mp3 by adding it into scripts .txt file. I already added the music to the mega patch 4 and I can send you the script file if you want.
-Remove those func_details outside the map that prevent it to compile with no vvis.