If I have an existing spread position opened through the pit market, may I close it through the electronic market?
Yes, so long as it's the exact same market, (size, contract month etc.) it is not a problem.
Yes, most definitely!
…along with all other financial Futures contracts. Seasonality occurs when there is a cyclical event that drives the supply/demand fundamentals consistently during certain times of the year. These events will occur with such high frequency they are called Seasonal Patterns. Read more.... http://lessons.tradingacademy.com/article/the-sp-has-a-seasonal-pattern-really/