You should build cubemaps in HDR first as a rule then in LDR after, And you dont need to restart map until you have built cubemaps for both, also if you have sprites in your map they may give an undesired effect in hdr if you dont kill them before building cubemaps.
sv_cheats 1
picker
ent_fire !picker kill
(get rid of sprites, then)
mat_hdr_enabled 1
buildcubemaps
mat_hdr_enabled 0
buildcubemaps
restart map (I normally exit mod and back again, I'm paranoid and like to be overly sure).
In 1.3 this is slightly different, I start map in HDR, kill my sprites then buildcubemaps then go to mod options and change my settings to no hdr in my gfx options (you can do this in game and it'll take you back to your map and you'll notice your sprites are still killed from world) so now you can go ahead and buildcubemaps again (ldr) and then restart map.
The bright weapon models I wouldn't worry about that has been fixed in 1.3. as for over bright lights yes, cubemaps & then a tonemap controller.
Does your map have an env_light? there are hdr settings for this that can be adjusted too along with the tonemap controller.
Here read this:
http://developer.valvesoftware.com/wiki ... g_Settings