While cost prohibitive, liquid yeast works a lot faster than dry yeast. To stretch the costs you can "wash" the yeast after fermentation and culture it back up to a half liter/liter starter and use it in another batch... I wouldn't do this more than 4 or 5 times as each generation the yeast mutates a bit. I bleev there's a TON of information on the matter from John Palmer. I think it's called How To Brew, and it's a free online book, or you can buy the paperback. I've read it too much.
Regarding two-stage fermentation, it really isn't a second stage you're just letting it settle out. I've left beer in primary until it was crystal clear before transferring and it worked just fine. The concern is that by letting the beer sit on top of the trub it will cause off flavors. I've left beer in primary for a little over a month and had no issues. Not recommended, but not THAT risky. Depends on your cleaning/sanitation habits.
I mainly use second stage for flavor additions like vanilla beans, fruit, etc... because whatever you put in primary or during the boil is going to get scrubbed by the yeast when they go to town creating a bunch of CO2. Something to keep in mind when thinking about what to add in the boil vs secondary. Like strong spices would be boiling material, but adding something mild like peaches would be secondary material as you are trying to protect the peach flavor. The common new brewer mistake is to just chuck everything in the boil, the result being a goofy ass tasting beer.
Besides.. when I rack to my kegs it becomes a secondary anyway... if you want to clarify quicker you can wait for primary to finish and then put the carboy in a freezer/fridge and chill it to 28 degrees. The yeast will fall out faster and not alter the flavor. Do not allow the beer to freeze, you just want it chillin... unless you're making an eisbock. mmmmmm.
/geek