Do I need to maintain my desired temperature until bottling or take it out of the "ferm chamber" after initial fermentation is done?
What about with long term brews such as sours?
It's best to keep it as constant as possible until the primary fermentation is complete. It can be critical when you are reaching the end of fermentation to adjust the temperature slightly as there is not as much heat being produced from yeast reactions. If the temperture drops a couple of degrees certain strains of yeast can flocculate too soon leaving the beer under attenuated. Secondary fermentation temperature is less critical and can be slightly cooler or warmer than primary.
For sour beers the initial fermentation temperature is the most critical as most brett strains will produce more sourness at higher temperatures. You can see some increased sourness if you age at higher temperatures but not as much as primary.
One item to take into consideration is if you are doing Lagers, you will need a Diacytl rest. This would typically be a 24-48 hour period at 55-60 °F vs the usual lower lager fermentation temps. This is usually done between the Primary and Lagering steps. This rest helps ensure your beer doesn't taste like somebody dropped a big bag of buttered popcorn in it.