STM32F103RBT6 has 128kbytes flash while STM32F103R8T6 has 64kbytes only. Both equipped with USB interface and 20kbytes SRAM. I found one minus point of this mcu; the compiling time is a bit longer than LPC2100. STM32 has Boot0 and Boot1 pins, on this board Boot1 is always 0 (PB2). To program, switch Boot0 to VDD and reset. To run your code, switch Boot0 to GND and reset. VDDA and VSSA are power supply for analog circuit (ADC and DAC), as usual make sure they are connected as close as possible to power supply to avoid digital noise come in to the analog circuit. Or, you can prepare a separated filter for analog power supply.
If you rich enough, of course you can buy a ready made development system costs 100-400USD but too much playing with software will make you less experience with the hardware. Try it and enjoy!
Below is example code of LED blink on PB5.