b- about the seated calf raise you have 3 options
1) use a dip belt and wrap it around your legs so the weight hangs between
2) Use a straight bar, put a type of pad on your lower thighs, and place the loaded bar on that and do it that way...
3) Load up a heavy dumbell and place it on your thighs, or between your thighs(i.e. one plate is on top of your thights, one is below.