Honestly, most of your frustrations seem to be related to the fact the FP2 is a smartphone, rather than problems related to the FP2.
You will not easily find a smartphone that lasts 3-4 days. It’s the drawback of having a big (touch)screen and a lot of power: basically, you’re carrying a pc with you, not a “dumbphone”, like your Samsung.
It’s true, FP2 battery life is rather short, even for a smartphone. I also would prefer a better battery (making the phone even bigger?). But I don’t expect my phone to last for 3 days…
Of course, you can also look around for tricks to let the battery last longer, like this topic.
Since the invention of the smartphone, I’m afraid 
Maybe this app would work for you? I didn’t test it, I just searched the web for “sms no conversation”.
The other questions seem to be answered by @AnotherElk. Here too, you’re searching for a function that has nothing to do with the FP2, but are general smartphone problems/questions. So, your conclusion not to recommend the FP2 to anyone, should be corrected to “I do not recommend smartphones to anyone”.
I can imagine the FP2 is disappointing to some people. For me too, some aspects are not as I would like them in my ideal smartphone. But before buying a smartphone, inform yourself. It can’t be a surprise the camera is not as good as the one from the iPhone, because the product details are easy to find on the website. Likewise, it can’t be a surprise the FP2 is a smartphone (with all the benefits and drawbacks).
And finally, I would recommend using this forum to look for solutions. Many issues have been identified, some of them can easily be solved. Just try the magnifying glass at the top of the page and start looking around. It can really save you a lot of frustrations!