Yes, you can certainly find boots that will allow you to walk successfully despite having weak foot muscles and bad posture, but then end result will probably be knee or back problems. In any case, you certainly shouldn’t be asking for advice on this forum. You have to go to the store and try the shoes on yourself to see what works. The brand name means nothing.
As for plantar fascia, that is an overuse injury due to weak muscles and tendons. You pushed yourself too hard too soon. You should have trained more in order to gradually build up the tendon and muscle strength before setting off on a long hike.
Having suffered various foot ailments over the years and finally cured them, I have come to the conclusion that for 90% of the population, shoes are a problem rather than a solution, and the remaining 10% of the population should not be walking long distances and certainly shouldn’t be walking with a pack on their back (this 10% is the people with severe structural problems in the feet). Our ancestors didn’t have fancy shoes. Also, even today people in the third world don’t have fancy shoes and many of them routinely walk 20 miles a day carrying heavy loads. And not with fancy backpacks either, but rather using a big bag connected to a tumpline around the forehead (no shoulder straps) or else a stick over the shoulders or else a heavy jar of water on the head.
For walking on most natural surfaces, barefoot is best. If you find yourself developing callouses and fissures in the heels or ball or big toe when walking barefoot, that means you are banging your feet too hard or walking improperly or else the skin needs more time to learn to lubricate itself properly–take your time, learn to walk softly and properly and there won’t be any callouses. You don’t need fancy lubricants or pumice stones or anything of that other junk. Coyotes and mountain lions have skin on their feet similar to our and they walk in the dryness of the desert without getting problems–we can do likewise.
For walking on broken scree or concrete, use loose-fitting sandals, since the human foot is not designed for extended distances on surfaces like that. For walking in snow, use breathable neoprene socks from campmor.com with sandals. (Avoid sealskinz socks as these are hard to clean and they become useless if they spring a leak, as they surely will when used outdoors with sandals.) Humans, unlike coyotes and mountains lions, are not designed for cold, so it is reasonable to bring along equipment to deal with that.
Walking on broken rock of the size used for railroad beds will force you to walk properly, since banging your feet and walking improperly will be extremely painful on rock like that. Note that the foot has 5 toes–all of these have a function. If you are not actively using each of your five toes to grip the ground as you walk, then you are walking wrong and will develop problems. Likewise, all of the smaller bones inside the foot and all of the muscles and tendons must be actively used. Also, the knees and hips should be loose. The end result of all this muscle usage is to compensate for different leg lengths, which everyone has to some degree or another, since it is impossible for the bone on both sides to absolutely identical in length. If you don’t use all the foot muscles properly, then stress of walking is transferred to the joints and tendons, which are not designed for stress and which have poor blood supply and hence heal slowly–this is the underlying cause of so many foot and knees problems in people who walk or run a lot.