Because I am still in New Haven, I would prefer [it] if the meeting [would be/was] postponed.
What is the correct way of saying this? I am curious as to with or without it, and would be versus was?
"I would prefer it if the meeting were postponed." Here's where you need the subjunctive mood to express a hoped-for or hypothetical outcome. More here if you need it.
If you want to delete "it," then you have to revise slightly: "I would prefer that the meeting be postponed."
The traditionally super-formal standard usage is one you left out, "I would prefer if the meeting were postponed." Were is the singular past subjunctive.
Almost no one uses this in contemporary US spoken English, and it's probably dying out of writing. More contemporary usage is still past subjunctive, which has come to be identical to past indicative: "I would prefer if the meeting was postponed." The conditional, would be, isn't standard in an if-clause.
Cf: The meeting would be postponed if he arrived late, but he isn't arriving late so it will go on as scheduled.