Nice 2hbh.
Not sure why you slice every forehand, but you can hit topspin with conti grip even on balls chest high, you just have to turn sideways much much more, almost a closed stance. If you like conti forehands, look at old vids of Panatta and Nastase.
Serve. You obviously has a strong swing. Problem is your low toss hand, leading to no body arch, so you swing straight ahead, when your swing should be up towards the ball. Look at the ATP logo, the one of DJ in trophy position. Notice his high hand at the end of the ball toss. Now look at EVERY other pro, man or woman, and notice the high hand after they toss the ball. That high hand helps your body assume the archer's bow, so you can swing upwards, even for flat serves, but especially for topspin and kick/twist serves.