Regarding jira Custom plugin

Hi Team
I am developing Rest end points and fragments in Jira using custom plugin
following doubts I have listed below:
1.issueservice: found in jira server but, is it available in Jira cloud if yes how can we use in custom plugin
2.using jira properties (JSD) sd.public.comment - how can we set in our custom plugin
3. How to get comment body without tags in jira cloud in custom plugin (rest Api) to use the validate Transition in jira cloud which is using issueservice inteface to get transitions
5. how to get list of all categories in scheme using Rest Api’s can we perform operations on inward and outward issues
7. source and destination objects (how to get the info in Jira custom plugin)

please resolve my above doubts on priority