Yes, as you noted, the visualization system in Perspective is completely different, and existing windows, screens, templates, etc will not be usable in Perspective.
Perspective does have a Python scripting backend, and all the system functions (that make sense) will work in Perspective as they currently do in the gateway/on the client. Some concepts do not directly apply, so there are some caveats here, but generally a script you wrote in Vision should either directly work or be easily adaptable to Vision. The except is scripts that did a lot of Vision-specific things (ie, navigation doesn’t work the same way in Perspective).
Yes, Perspective has support for SVGs (in fact, probably better support than Vision). Expanding the “primitive” drawing support is also on the roadmap.
Alarm pipeline configuration
Alarm pipelines will work exactly as they did in 7.9 - nothing has changed.
Tags have been significantly restructured, but we’ve gone to great lengths to keep things from 7.9 working as smoothly as possible. Query tags should not be significantly affected by the changes in 8.0.
To go with query tags - UDTs should generally upgrade smoothly, and some things will get a lot more powerful/easier to do in 8.0.