To add clarity to the above posters comment. The yeast take 2-7 days during primary fermentation to create the drop in sugar and in doing so create CO2 and ethanol, they also excrete esters, fusel alcohols and other “bad” compounds called VDK and/or diacetyl. The next 2-7 days the yeast are rebuilding their reserves and preparing to go into dormancy. While they are doing this they also go back and re uptake the VDk and diacetyl.
If you were to keg right after primary you would prevent the re uptake of VDK and diacetyl and the beer would be “stuck” with off flavors. Common VDK compounds create green apple, banana and buttered popcorn off flavors along with a host of others.
So there we have two full weeks if your ferment was normal and healthy.
Then you can transfer to a secondary if you wish for another week to drop more yeast and trub and keg at the end of week three-four for most common beers. If you wish just simply skip the secondary and keg after week two if the beer is of low gravity. I find the third and fourth week in secondary helps to also condition out some of the young “green” flavors better than if I keg right after two weeks. YRMV
Quick tip: liquid yeast typically needs to be started with 1-3L of wort before pitching to a normal 5 gallon beer, plus you need to add oxygen to the beer before adding yeast. If using dry yeast strains when learning the basics you have more than enough cells in a sachet of yeast for a 5 gallon beer and dry yeast doesn’t require the cooled wort to be infused with oxygen. So just a super easy way to ensure your first beers have the nessecary cell count and reserves built in to ensure super healthy ferments. Also if no one has introduced you yet, check out mr malty.com and he has a yeast pitching rate calculator that shows how much liquid starter to make or how much dry yeast is required for the beer you are making. See the link below to check it out, its an invaluable tool for yeast
http://www.google.com/url?sa=t&rct=j&q= ... Sg&cad=rja
Kegging and trying to pressurize at room temp is problematic because CO2 dissolves into solution much better at lower temps(serving temp)although you can do it.
To answer your post you can either add sugar like you would to individual bottles and use CO pressure to simply “push” the beer as it will be carbed from the yeast and sugar. But this method is fraught with issues, SO to make things simple you attach the gas to the keg and let it carbonate with the bottle of CO2 and then it is also drafted with the bottle of CO2. So NO additional sugar is used.
Before getting into kegging basics it is pointless to give advice for room temp if you plan at some time to eventually have the keg in the coldbox served cold. What exactly is your plan here?
