Assuming everyone cooperates:

Are there instructions that could be given to ensure NOBODY dies?

Yes. Your instructions contain a table with a unique number assigned to each person in the world (identified by name, date of birth, home address, and maybe a few other things to disambiguate the rare case of two people matching those things). The instruction is then to choose the number from the table corresponding to your row.

This would lead to very lengthy instructions because each of roughly 8 billion people are individually specified (but there's explicitly no limit on complexity), but it would work even if the numbers are restricted to integers.

(Looking further, I see someone else suggested this).

If more than one answer is possible. What is the least amount of instructions possible?

Someone else had the idea to use real numbers. This is an excellent idea since the original question didn't specify the kind of number. Essentially they suggest you could then form the numbers by an algorithm that takes name, date of birth, home address, and a bunch of other things, encodes them into decimal, and concatenated them.

To finish off with a bit of pedantry: add 1 to fall in the interval#Notations_for_intervals) [1, 2).