Welcome 5inch and dwight - congrats on starting. I’m just starting up the newbie routine tonight (though have been doing some Fowfers for a week). I did three weeks of PE in 2002 and finally got back around to it.
5inch, I think you’ll find that most people gain length more easily than girth (though definitely not true for everyone!), thus making your goal of adding 1.5 inches of girth while only an inch of length an unlikely proportion. The good news is, if you gain 1.5 inches of girth, you’ll probably have gained 3 inches of length! (That said, I haven’t noticed many stats boasting 1.5 inch girth gains, though I’ve definitely seen stats where that has happened. Quite common to see 1.5 inch+ length gains.)
Dwight, congrats on your gains! Our starting measurements are similar, so I hope to make a similar report in one month’s time. Have you calculated the change in volume? I bet it’s an awesome stat. As per turkey neck, I recommend doing a search on turkey neck. Pretty much has been said on that and there are at least a couple different opinions on what actually causes it. Some people believe excess skin causes it. Others believe not enough skin causes it. Depending on what you believe will inform how you decide to prevent it. Best o’ luck!