How far away can I scan a bar code?

Scan distance is affected by many things; the type of scanner, type and size of the bar code, material on which the code is printed, and environmental conditions (mainly direct light).  There's isn't a "one size fits all" answer.

What is the best barcode to use for warehouse locations?

Typically Code 128 for standard linear codes and Datamatrix for 2D codes - these provide the best X-Dimension for reading.

What is the range of a blue tooth scanner?

Most BT cordless scanners will provide at least 50' line of sight from the scanner to the base unit.

What is the best scanner to use in bright / sunny environments?

Imagers do a better job reading codes in sunlight than laser scanners.