I enjoy my rollers but never got very confident on them. I don't have a huge amount of space to safely wipeout on them, so I don't tempt fate by switching from hood to drops, drinking while riding and taking my weight off the saddle. I have a little plastic foot stool on either side of them for starting / stopping. To start I clip in on foot and start pedaling with one leg to get the wheels moving before carefully getting the other foot onto a moving pedal.

Mine have no resistance unit, so I always use the big ring and bottom half of the cassette. Minimum speed is usually over 40 kph, so I just move the wheel magnet out of the way since the distance numbers are meaningless. I find the rollers very easy to get a good workout, no problem at all getting my HR all the way to the maximum. I play around with cadence and resistance while riding on them going as low as 70-80 in my highest gear, all the way up to 120-140 in easier gears. 130+ RPM takes a LOT of focus.