First, its not a secondary 'fermenter'. Its a secondary 'vessel', 'tank'...or just 'secondary'. No fermentation should be taking place in secondary.
Typically a bucket with a spigot is for bottling, not fermenting. as long as you pay strict attention to sanitizing that spigot inside and out, taking care to remove it and clean it thoroughly between each batch, you can use it. However on some buckets it is very low, and you'll drain some of the yeast cake into secondary, which is what you want to avoid.
I would invest in an auto-siphon. Siphoning is your friend, since most secondary's don't have a spigot (unless you've got a 5gal better bottle w/ drain). Secondary needs to be glass or PET plastic...no buckets.
You will indeed lose some beer, sacrificing a few ounces to avoid trub and yeast. You can tip the bucket carefully to maximize your yield.
Irish moss is useful. use 1 tsp. added about 20 minutes from the end of your boil. secondary finings are typically isinglass or gelatin. I only use irish moss.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10