How many FPS would I get with this Graphics Card?

Well i have a very similar one but it mainly depends on the CPU and RAM too. I have 1.30GHz cpu and 4GB Ram with similar graphics card and get minecraft frames of 10-30 fps on average on minimal graphics and render distance of less than 10. You may get better

On the lowest settings, you should get 30+ FPS in minecraft, 20+ if using higher settings. It is a low-end graphics card, so there's not much it can play.

Radeon HD 8400 is an integrated graphics card on some of the Kabini APUs. Integrated GPUs leave a LOT to be desired.