When the request routes through HR rather than your manager, the letter needs to stand alone without context. Include your role, tenure, last review date and a summary of achievements your manager would otherwise supply verbally.
Yes. An unspecified request forces the other person to guess low or defer the decision. A figure gives them something concrete to take to budget.
Only if the recipient does not already have it in front of them — usually they do. The field is optional in this builder for that reason.
Ask what specifically would need to change, and by when. A documented answer turns a rejection into a plan with a review date.