Like some electronics, this linear motion Pico servo doesn't like running at over 5V. Even slightly less is better. This adapter board adds a bit of voltage drop to a 5/6V system to make your servo happy.
XBee is good; Synapse is just better. More I/O, embedded python, and generally better range at comparable cost! This particular module is 2.4GHz with OTA (Over-The-Air) speeds up to 2Mbps, maximum 450M (1500') range and a chip antenna for compact installation.