u can check whether u have ofw/cfw by pressing *#0000#.
On the custom version, it will show your current version which should be 32.0.002, like mine showing symbian anna v7.
(fix me up if i'm wrong)

You can use the app which mention on the thread 1st page.

It's a custom firmware actually.
U have to flash your phone, don't do it if you still want the warranty though.
Otherwise U will the OFW which offer little to be desired when u update it.
Pros, a lot. Quick application boot up, no need to sign app, battery saving up to 4 days on normal usage rather than original firmware 2 days. And the list goes on.
Cons, a lot of cfw out there, pick one that suit u the most. Maybe u like it, maybe u not.
Even scrolling the previous page on some of our regular poster said about shadow 1.5cfw, it look good though.
In the end, its the matter of preference. 
Why don't u search around a bit on info for flashing. I believe there is some in this forum. It's not a rocket science though. Quite simple actually.