Kegged beer will last quite a while. The main factors that would spoil your beer is light and temperature. Keep it dark (No problem in a SS Keg) and keep it cold. The higher the ABV of the beer, the longer it should last before it turns. In my personal experience, my beer usually lasts 6-8...
The flakes are most likely little chunks of yeast sucked up the racking cane when transferring your beer from fermenter to keg. It happens all the time to me no matter how careful I am. The only way to get rid of them for sure is to filter your beer.
I'm personally a fan of Brewer's Friend for creating my recipes. They are half the price and do the same thing if not better. They even have a free trial version. http://www.brewersfriend.com/
For big boy Fermenters (Anything over 10G in Stainless) I always recommend our friends Stout Tanks. http://conical-fermenter.com/products/conicals/ They do amazing work and you'll have a piece of equipment that will outlast you with proper care.
Now if you don't want to skip a house payment...