A half sleeve is the most common way into large black and grey work: it is a real piece, it can be finished in two or three days, and it does not commit your whole arm.
The one thing worth doing properly is designing the full arm now even if you only tattoo half of it. Extending a half sleeve that was never planned usually means covering work you already paid for.
Two to three full days for most designs, spread out with healing time between them.
Yes. It costs nothing to plan and it is the difference between extending the piece later and covering it later.
Upper, usually. It hurts less, it heals easily and it is the part most often on show.
Yes, and that generally looks better than three separate tattoos sharing an arm.
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