1. The relevant rule is from AIP RAC 4.2.5:
2. "If a pilot is required to cross any runway while taxiing towards the departure runway, the ground or airport controller will issue a specific instruction to cross or hold short. If a specific authorization to cross was not received, pilots shall hold short and request authorization to cross the runway."

1. Unless specific instructions were given to cross the other runway, the pilot must hold short and ask or wait for clearance to taxi across.

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2. You do not need specific clearance to cross other taxiways, as long as you stay on the taxiway you were directed to take..

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3. Absolutely not. There might be aircraft landing before you will be cleared to leave.

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4. A clearance will normally include "hold short" or "cross" the other runway, but if it doesn't, you must stop.

1. This is a common question for schools to mismark. I used to have it wrong on here, even. If your instructor marks it differently than I do, politely point out the AIP section, and ask for an explanation of why your answer is wrong. Some instructors are willing to admit to mistakes and some aren't: you'll find out which kind you have.