For the outside of the figure 8 it is understandable that Chloe lags. To keep in the correct position she needs to quicken her step which she doesn't have to do when walking on the inside. It is possible that that increase of speed that is needed would naturally take her into a different gait that would make her go too fast, experiment with different speeds of walking when turning and see if this is the problem.
Here are a few possible fixes:
- Speed up a little when practising the turn with Chloe on the outside - when a dog lags we tend to slow down so over time the dog goes slower and slower. If you speed up on the turn instead of slowing then Chloe might realise she has to hurry a little to keep up.
- Start with Chloe beside you and turn away, reward her for finding heel position again. Walk a step, pivot, turn, have her repeatedly 'find' the correct heel position after one step or turn. Once she gets the idea of the game make it as hard as you can for her - turn fast, slow, different directions, full turns, fake turn one way then the other. Over time you should get to the stage where you can't lose her no matter how hard you try. Use treats rather than play rewards for this to keep the flow of training and a high rate of reward.
- Use your rewards to pull her forward into the correct position, if throwing a ball as a reward mark on the turn and throw the ball on ahead of you so that over time she will tend to move up in anticipation. If rewarding with treats try rewarding on the turn with a treat in front of your leg.
- Work on her keeping pace with you pivoting by rewarding perfect position at different speeds then gradually widen your pivot into a turn.
- Go back to basics, walk a straight line marking and rewarding in the correct position. Gradually start to introduce slight curves still rewarding perfect position. Over time make the curves into turns, if ever Chloe lags don't reward her but make the curve a little straighter for a couple of attempts before you make it more difficult again.
For the talking you probably need to look at how you are rewarding her for talking - she's only talking because she finds it rewarding and that is probably linked to you talking as she talks when you do. Does she talk when you practise or only when you work a real course? Have you tried stopping work as soon as she starts to talk? I'm sure you only ever intentionally reward her when she is silent but what about becoming quiet as soon as she starts to talk?