Does anyone go and check questions on hold and make a decision about them?
They are deleted, subject to a specified set of conditions.
There is a automated cleanup process for this. The script is known as the roomba:
The system will automatically delete closed (not as a duplicate),
unlocked questions with zero or negative score having no positively
scored or accepted answers or pending reopen votes, that were closed 9
or more days ago and haven't been edited in the past 9 days.
The system will automatically delete unlocked, unanswered questions
that have negative score after 30 days.
The system will automatically delete unlocked, unanswered questions
with score of zero (or one if the owner is deleted), fewer than 1.5
views per day on average, and fewer than two comments after 365 days.
Source How does deleting work? What can cause a post to be deleted, and what does that actually mean? What are the criteria for deletion?
Note that individual sites may be their own customised criteria. The specific ones for Super User can be found at The Community user deleted my question! What gives?
What does it mean for a question to be on hold?
If a question has been closed (except as a duplicate), then for the first 5 days, it is marked as “on hold” rather than “closed”. This is meant to convey that the question requires improvement and may be reopened if improved. During this period, if the question is edited by the asker (now by anyone), it will be added to the reopen queue. Other than this, there is no functional difference between “on hold” and “closed”.
Source What is a “closed” or “on hold” question?