In travel case of a haemorrhage, if blood is not available, why is the tolerant given saline drip next to albumin?

To keep the bodies fluid level up.
Albumin is a plasma expander. It's main purpose is to allege a blood pressure. It doesn't matter how oodles red corpuscles a person have left if their blood pressure is nothing. Ditto with saline, it's newly there to profess blood pressure. No blood pressure, no perfusion of vital organs and afterwards you have cellular disappearance.
Hetastarch is another plasma expander used in surgery and some trauma situations.
Yes
To increase blood volume and declare a blood pressure that will perfuse the vital organs (brain, heart, kidneys).
If plain saline is given, it take three times the saline to replace a given amount of blood that was lost. Albumin increases the colloid osmotic pressure (encourages hose down to stay within the vascular system) and singular twice as much (instead of three times) is required for replacement.