I bought the MGI Zip Navigator AT bundle through Costco a few months ago, and thus far I love it. My goal was to be able to walk further into the summer here in Phoenix, but the ultra-hot weather has already rolled in, so Hodor (you absolutely must name your cart) is in hybernation for now. The model I have is a little different than the one found in many golf retailers, basically the front end is beefier (which helps on rough terrain.) My advice on some of your questions:
1) Make sure you get one with the outrigger wheel on the back, definitely helps prevent tipping backwards.
2) Remote is the way to go. Once you get used to it you'll wonder how you lived without it.
3) Lithium battery is worth it, most of the high-end ones come that way.
4) Although the MotoCaddy was rated #1 on this site, the MGI was also rated highly. To be honest, they look so much alike I'll bet they're made in the same factory.
Good luck with the shopping.