First of all, yeah a 1/2" pin is just fine. Pinch skin as necessary to make sure you're still dealing with fat tissue (don't accidentally muscle it). And yeah, little localized bumps like that are common. If you inject sloooowly (btw, do *everything* with GH slowly) and gently release the pinched skin as you are injecting, the welt will be smaller and go away faster. I don't rub my welt afterward, just out of paranoia that I'll break some of the HGH (yeah, that's silly I'll admit).
You'll soon notice that you lose fat around your injection site. I stayed close-ish to my naval at first, the worked my way out some, and currently inject all the way into my love handles. It can't hurt to keep the site moving around some.
Also, you may want to come out of the gate at 2 IU's/day and build-up to 3. Chances are you'll get some joint pain around week 3-4 and if you are at 2 IU's and gradually go to 3 (or even 4 or 5) it will be smoother. Don't let the join pain freak you out btw, it passes.
And finally... dosing. I've read that 2-4 IU's day = fat loss and general well-being. I don't think the anabolic effects kick in till 5-6+ IU's per day for a lot of people. NOTE: If you are mixing HGH with AAS, disregard the 5-6 IU's per day comment. HGH seems to have synergistic effects with AAS -- kinda like mixing a pain pills and booze.