Regarding your first question where all objects on the slide are visible in Edit mode regardless of where the timeline pointer is located...This is standard Captivate behaviour. The app may be capable of publishing to SWF/Flash, but the editing environment does not work the same way as Adobe Flash does. So you need to get used to this difference. After nine versions it does not appear likely to change.
As to the 'jittery motion' I cannot say what the issue might be without more information. You may simply be expecting too much, or you may be using the app in the wrong way. Hard to tell.
I think you are correct that Captivate is not intended to be an 'animation app'. It's primary purpose has always been to create e-learning courseware, not animation. The animation features have been progressively added over time in response to user requests. Expecting it to behave the same way as Flash or After Effects will only lead to frustration. And once you start publishing out to HTML5 the limitations you will encounter in that environment as far as animation goes will only increase the frustration. (And if you were hoping Storyline would be a better option I can assure you from personal experience it is not.)
As a person who also came to Captivate from the Flash world, I feel your pain. When I run up against too many limitations in Captivate's animation abilities, I find myself still going back to create sophisticated animations in Flash and then import them into Captivate as SWF. When Flash is reborn very soon as Adobe Animate, I will probably be building these animations as OAM files and importing them into Captivate instead of SWF.
I think the best advice I can give you is: If you want to be completely happy with Captivate's animation capabilities, you need to lower your expectations.
Captivate is an eLearning authoring tool, not an animation tool at all. Use the right tool for your goals! Use Powerpoint for Presentations, Flash, Animate CC or Edge Animate for animations, Captivate for eLearning courses.