New to hps and mh. Need help

Nice set up.
 
Trash that fan though... You're going to need a nice 6" centrifugal fan, not something like that, those fans waste energy & won't do you much good for anything else other than circulating air around the tent. Downside is the centrifugal fans are more expensive but you can search on craigslist for a decent one. I got mine for $35 on cg; uses ~120watts & lots of cfm. (I recommend getting a $18 fan controller off eBay to make it quieter and slow it down a bit for more heat transfer)
 
Also... If you're wanting to use the air cooled light fixture also to create negative pressure in the tent (assuming it's a closed tent) take off the ducting on one side & leave it open. Place your new 6" centrifugal fan outside the tent hooked up to the ducting so it's sucking the air out of the housing, not pushing through. 
 
You want the suction coming out of the tent as high as possible because heat rises & you want to suck that hot air out, and cool air stays at the bottom so you want your passive intake near the bottom sides of the tent. Again, nice construction work.
 
 
Open End -> Light Fixture -> Ducting -> CARBON FILTER -> 6" Centrifugal Fan -> Out.
 
That's a simple exhaust system with one fan. What I use is:
 
1. (Outside Tent) 6" C Fan [Pushing] -> Ducting -> (Inside Tent) Light Fixture -> Ducting -> (outside tent) -> Vent outdoor.
&
2. (Outside Tent) 4" C Fan [Sucking] -> Ducting -> (Inside Tent - Placed near top side of tent) -> Carbon Filter.
 
#2 will create the negative pressure in my tent to allow no air to escape & be filtered. (as well as bring in fresh air from passive vent on tent)
#1 will cool down my light and transfer the heat out the window.

 

I tried using the system you have before and it created too much heat. (I use a 1000W system though...)
 
Anyway, MH bulbs will not turn back on for a while if they are turned off. The gases inside the MH lights take a little bit to heat up before they ignite. There's a few stages which is why they turn on, and the light slowly gets brighter. The gases ignite in stages in a way using an arc ignition (similar to TIG welding).  I don't know the specifics but you can google that. If the power gets interrupted & turned off, just wait 10-15 minutes for the gas to cool down & then turn the power back on. Voila.
 
The yellowish liquid I'm not sure about, its probably from the arc or the gasses, not a big issue imo. I think mine have the same thing; I'd have to check. Bulbs do have a certain life span so don't worry most MH should come with a warranty anyway, so make sure you keep the receipt if anything goes wrong.
 
 
If you create the method I have with your setup, you will get excellent heat transfer & everything will stay nice & cool. The light housing will be cool to the touch, the glass will always remain a bit hot to the touch though.
 
(Keep in mind an electrical circuit only has so many amps. Make sure your house circuit (not outlet) can support the energy you plan on running. That's why energy efficiency is so important so you don't blow a breaker, like I have... One bedroom per circuit is common. Each circuit should have a 15-20amp max load)

 

You should also try to shorten the length/curviture of your ducting so you can get the most cfm and effeciency.