I feel your pain on the slowing down. When I first started TI training, I got so into focused, slow swimming that I forgot how to speed up. It took along time to get my speed back. It will come when you get solid with your stroke and start doing some tempo work again. It is hard to be patient. When you feel consistent in your stroke, start playing with holding s/l as you very gradually increase tempo. The speed comes very quickly in that phase.
The spearing is the shape of the arm. The idea is simply that you want your whole arm to enter one whole in the water and carry as few bubbles as possible. As for the speed of the arm, I believe the arm should gradually increase in speed from setting the catch through the end of the spear so the spear is the fastest part of the arm stroke. However, when most people think about the speed of the arm, they end up punching the water without attaching their body to the motion. I like to say "speed is your enemy, momentum is your friend." Not much works in the water that is punchy. Smooth movements with weight behind them are much better.