I have one domain on which i am trying to get as soon as it is released and it has 2+ years on its age and basically I am wondering if i register it will it keep the domain age (or its original creation date)?

Also,

i have another old domain that i had registered 4 years ago, but never renewed it. And anyways, if i re-register it will i have the domain say that it was created on that original creation date? Or will it be a new creation date?

If your registering it then it will have new creation date on it, but if your transfering or renewing it will keep original creation date.

If that old domain your talking about is aviabile to anyone then when you re-register it, it will have a new creation date as it will be setup as like a brand new domain.

creation date will be counted from the date you re-register.

however if you want to check old data you can use

http://www.archive.org/web/web.php

There are some exceptions, but this is not your case.

Sometimes people pay for a domain, and after about 2 months, registrar recognizes fraudelent order and holds the domain, and then sometimes sells through auction. In this case, original date is kept.