If I receive a 14 day ban for my first offense, is my next punishment a perma?
Yes. Once you're on a 14-day Suspension, any punishment of any sort - whether minor or major - will result in a permanent ban.
Also, if I don't get reported for a certain period of time does my punishment ever change? For example, if I play clean for a year will I still get permad or would it be a chat restriction etc?
To the first part, yes - as long as you show sportsmanlike behavior, over a certain length of time (it's fairly long, as far as I know), your place on the punishment ladder will drop. The first step down would be the 25-game Chat Restriction tier, where any punishment (disregarding major ones) will result in another 14-day Suspension.
Over enough time, your account can fall back into good standing as though you hadn't had the 14-day ban in the first place - though I think it will still remain on your record that you had one at one point.