Hi there, SeaGal, welcome and thank you for signing up to our ever-growing forum.
It seems like quite a few Crosstrek owners, or soon-to-be-owners, consider(ed) the Xterra or are coming straight from an Xterra but couldn't quite do it for different reasons -- too big, not good enough gas mileage, more than they needed in a truck, etc. It sounds like you really know your way around cars and did your due-diligence in researching your vehicle purchase and we are very happy you went with the Crosstrek.
I have had mine three weeks now and have been loving it more and more every day. I actually leave tomorrow morning for a three-day, cross-country drive from North Carolina to California so I will really be putting the Crosstrek to a highway test and of course I will post about it.
As far as image resizing, I have used this website when in a pinch, http://www.picresize.com/
and it seems to do the job just fine. You can select how big you want the picture to be by height and width and/or maximum file size. Either that or use a free online host to upload your images and put them in your post. I highly recommend imgur.com -- it's free, no signup required, and very easy to use.
Again, welcome aboard and we look forward to your input on the forum!