I've got a few questions regarding my glock.
I want to do some stippling and reduction to the grip of my G19; will that void my warrenty? Or does the warrenty even matter?

Obvious answers are obvious.

Ha thanks man. I just noticed that you can only apply for the warrenty within 30 days of purchase, and it's been well over 30 days since I've bought my glock. Oh sell I never plan on messing with the internals of the gun since it's my EDC.

Plus, Glocks are Glocks, they run no matter what.

Try some talon grips before you start hacking on your frame, you might like them and they won't break the bank. http://talongungrips.com/grips/glock/

Cold Bore Customs seems to have decent prices on stippling FWIW

Glock will fix your gun if the problem is not stippling related.
And even if you are the umteenth owner.

You don't need to mail in the warranty card to be covered under the warranty.  If you stipple the grip and then break the frame Glock might charge you for a new frame, but if you need warranty work on the rest of the gun Glock will probably still cover it.  Glock has excellent CS.

Glocks do tend to run great until you start messing with them- no shortage of posts in every glock forum about I put xyz aftermarket part in my gun now it won't work!
The fix it until it breaks cliche

I've been running Glock pistols for the past decade.  As long as you don't have a, 'Glock problem' that is incurable - like, say, a model with an ambidextrous safety - you don't need the factory to fix your Glock.  I've sent Glock pistols to Smyrna that had real problems when I sent them in, and still had real problems when I got them back, too.

My suggestion?  Learn how to fix your Glock pistols yourself.  Glocks are (relatively) simple mechanical devices.  If you make an effort and teach yourself how, there are no expensive trips to the factory, no tongue-in-cheek factory bullshit excuses, and whatever parts you need are available from numerous aftermarket vendors.  How do you learn to fix your own Glock?  There is a plethora of, 'how to' books and instructional videos available for anyone - except those who are completely mechanically inept - to learn from.  

Fixing a Glock isn't, 'rocket science'.  As a matter of fact I've been waiting for more than three years, now, for the Glock factory to finally fix the crappy MIM extractor on my G-19.  It doesn't work well like the machined steel extractors on my other (older) Glock pistols do; and, even with a dozen trips to the factory in Smyrna it ain't ever going to work like the old steel extractors do.  If you want to stipple your frame I'd say to go ahead and do it.  There are far more serious Glock problems, and potential Glock problems out there than simply stippling your frame.  (Which I've, also, done; and, trust me, there is no adverse effect on performance.)