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Daytrading Stocks

I've mainly daytraded futures until now, but would like to incorporate some stocks into my routine to keep me busy since my methods haven't been producing many signals in the futures here lately. So I have a few questions regarding what stocks to consider for trading.

What's the minimum daily volume a stock would need to have?
What would be the minimum share price a stock would need? (or does this even matter so long as it's not a pennystock and has volume?)
What is the max spread that is acceptable? I know this varies from stock to stock but what is an unreasonable spread?

Any other advice or words of caution are welcome.