All the 2016 Panasonic models have the narrowest viewing angles from a VA panel losing colour as early as 16° off center.
I have only seen one review of one of their 2017 models and it looked like they improved, that was of the EX-700. E=2017, D=2016. Sadly though the 2017 models aren't great value at the moment, plus i'm not sure exactly how the higher end ones fair. Certainly overall I don't think the EX-700 is worth the extra over its now discounted priced DX-700.
1. The best time to buy a tv is a year behind the release of them. Right now we're getting towards the end of 2016 stock being available which is a risky time, nice bargains are to be found, but stock is running low and will soon sell out. It could be too late depending on which model you are looking at buying. The most sensible thing to do would be to aim at a 2017 model you like the sound of and purchase it either a bit earlier next year or at least wait for deals to start at black friday onward.
2. You should always get the largest screen, this is especially the case with UHD as you need to view approximately twice as close vs FHD to benefit from the extra resolution. For many people this makes UHD pointless though as the majority of people don't view close enough. The optimal viewing distance for a 65" UHD is 1.2m whilst for a 65" FHD TV its twice that. The only time I would go against this rule would be if there is too much of a price difference going larger like there is with the OLEDs or if you could only pick up a very bottom of the range tv in your budget at 65".