Again, there's a lot of internet lore and lack of factual information already forming in this thread, without having needed details first. Brand A poly at an 80 durometer vs brand B at a 60 will give you a much different experience, with rubber being around a 45-50 typically. Not all poly is the same.
Superpro is one of the better brands out there, only reason I back it and sell it. They run around a 60-65 with stiffer options for certain bushings.
Depending on planned use for the car, what platform you're running, if you are super nit-picky vs. really relaxed on expectations, etc, all of that can play into what route you go. If you do go poly, please, for the love of god don't go cheap like URO or MTC, as you will regret it and it will taint your impression of the material.
Having full poly in my 140 and 740, have for the last decade, I don't regret it one bit, but I also planned for a very sport minded ride. The difference between stock and poly in terms of noise, vibration and harshness is minimal.
As for order of replacement, really doesn't make a difference, but I'd be smart about it. If you have blown out bushings, do those first, then do the rest. Fronts have fewer bushings to replace than the rear. Adjustable torque rods can be bought with poly already installed, making it easier. Level of skill, work area, and tools will play into what you install as well, as some will require a press, most will require a decent bit of work, usually less work to install poly than to install rubber though.