No FFD, pressing the brackets (“[ ]”) by themselves will either decrease or increase the size of the brush while the brush tool is active. Also while the brush tool is active, holding the “Shift” key while pressing either “-“ or the “+” will change the brush’s hardness from soft to hard respectively.

Yes, I agree with AthenDesign that making the brush as large as Photoshop allows will allow you to then stamp it onto its own layer. This will allow you to then resize the layer with the brush stamp on it to whatever size you need for the job.