Like many suggestions, there are already existing Feature Requests that cover your ideas. We prefer a single forum topic per idea, so please add your comments to the existing discussions as appropriate.
Per your #2:
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Feature Request: Turn intensity up/down in % blocks in addition to % points
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Continuous Press, Quick Intensity Adjustment [Feature Request]
Per your #1, with the addition of Adaptive Training, that method of extending the workout is not really the best method if you aim to add more than something like 5-15 minutes. If you want to add 30 minutes or more, you are better off to finish the first workout, and load a separate session that suits your duration (not to mention intensity, which side-step #2 above).
I am tempted to refine this topic into a feature request about just your #1 idea, following the forum preference at the very least.