doubts regarding fpga spartan3E kit use.

I am newbie in using FPGA and while using spartan3E starter kit I have two
doubts.
1.I am making a simple ADC to DAC system using on board ADC and DAC
chips.Do I have to provide 3.3 volt( for creating reference voltage) to
header J5 through external power supply, or does the board has its our
circuitry to provide that internally(from its own power)?I think same will
go for GND too.
2.I have to store samples coming from ADC ,store in memory and do
processing on them.what will be of better use, FIFO or RAM?and how much
memory is available,because it seems I must obtain more than 1 Mega samples
per cycle for my purpose.