Q1: What do I need to order so that I can program the Seeeduino Stalker V3 from the Arduino environment? I assumed that the Seeeduino Stalker had a USB connection for the Arduino IDE, but it does not.
A1: You would require a USB to UART board like UartSbee v4. Please read more here.
Q2: If the connected UartSBee V4 is set for 5V, does the Stalker automatically drop the voltage to 3.3V for the onboard Bee plug in?
A2: There is an LDO that converts 5V to 3.3V. Hence, you could use 5V setting in UartSBee.
Q3: Are the analog and digital Arduino pins (D0-D13 and A0-A5) working at 3.3V or 5V?
A3: All the I/O are 3.3V Logic.
Q4: Are the I2C and ICSP connectors running at 3.3V or 5V?
A4: I2C port has a logic level translator that can support 5V if VCC is 5V. ICSP is 3.3V.
Q5: Will the VCC connection on the board be 3.3V or 5V?
A5: The board including the MCU, XBee etc.. works on 3.3V VCC.
Q6: After I program the board and do not need the UartSBee V4, what are the different ways that I can power the Stalker? Can I power it through the solar connector and if so, what voltage(s) are safe? Can I power it through the VCC connection, and if so, what voltage?
A6: The Stalker V3.0 can be powered by Li-Po battery(3.7V). The Solar battery is used for charging the Li-Po. It needs to be a 5V solar panel ( uses CN3065 charge controller IC).