What is the time limit to a video that I can upload to YouTube? Is there an upper video length that I have to make sure my uploaded videos are under?
Are there other limits or restrictions (quality, resolution, etc) to a YouTube video?
Generally the limit is 15 minutes, although YouTube has raised this for users who have a good history of compliance with their rules.
The current limit is 15 minutes.
if you upload a lot of videos and you get roughly 50-100 views on each video then they will increase your time limit to unlimited allowing you to upload any length video.
Youtube got rid of the 15-minute time limit late last year for "well-behaved" users:
http://gigaom.com/video/youtube-upload-limits/
You can post up to 1080p.
I'm not a Youtube uploader, so I don't know under what rules certain user categories fall under, but I've seen videos that break the 15 minute limit by far. So I would guess that 15 minutes is not the upper limit, only that you just gotta figure out the terms of agreement.
Two examples, one lousy called Longest video on Youtube (not worth your time, except as an example) and the other - a movie actually - The man who would be king (well worth your time, IMHO).