4 tracks, recording, playback is surely fine. Various FX is also most likely ok depending on what you are asking for. As in: each DSP algorithm implementation will have a very specific CPU cost and so here your mileage may vary depending on the algorithms you are trying to implement. I am fairly sure you will be ok.
As for inputs, you get as stock 8 analog inputs (for pots/sliders) and 16 digital I/O (for buttons/LEDs). If you need more, you can expand the number of analog inputs with the multiplexer capelet, which gives you up to 64 analog inputs.