Per 1) It is always off. Basically, I run indicators off the completed bars then place market orders.
Per 2) I swing trade stock indexes and day trade commodities always out before EOD.
Per 3) Futures Only and ETF for stock index futures swing trades.
Per 4) Each one of my system can arbitrage every market, but the best results I've found must have some analysis for efficiency so I use the efficient market frontier to determine what's best. For commodities most investors are more comfortable with commodities being out before the end of the day.
Per 5) I would say the strategies are World Class Complex Genetic Algorithms.
Per 6) This can be measured through the Efficient Frontier so there is a mathematical definition I use to analyze when to use them.
Per 7) I don't know, but the APD in backtestests is around 0.7 with profit factors greater than 1.6.
Per 8) They are percentage stops and the indicators as with the swing index systems have a factor to play in closing trades. Time stops and a combination of the two also work well for day trading.
Per 9) I've not seen strategies that would buy the open are necessarily that bad, but EOD is more determined by the day trading strategies I use particularly in Corn and Gas markets where EOD is found through genetic optimization and so do not get out EOD without also being before the times where they might close in their Open Outcry Pit Session Times.
Per 10) I've never understood the need to be both long and short in a strategy but primarily for swing trading indexes I find one system overrides what might be conflicting directional hedges and for daytrading I'm purely directional with time based exits and percentage stops but also could be out based on the same indicator.