Practicing push hands, even with WC stylists, is a far cry from learning how to handle a real punch. If for no other reason than that there are no punches of ANY kind in push hands. However, I agree with you that actually dealing with punches is the only real way to learn how to handle them.
Constant and correct practice of the opening and closing movements of the forms can help to understand the effects of fajing, but don’t do much to specifically target its development directly. As with the punches, the best way to develop good fajing is to practice fajing.
Your development of applications is certainly traditional, and your point regarding confidence is often undermentioned, IMO. However, it is important to know that each posture does have codified applications at different levels; it’s not a different set for each student.
Your next reference to large frame being what is learned first is relevant to Yang Cheng-fu style, but not necessarily to other styles of Taiji, including original Yang Lu-chan style. Although, I’m personally a huge fan of moving naturally from large and slow to small and fast. If you can feel the spring being loaded with chan siu jing in your lu practice, it sounds like you may be well on your way to developing real fajing.
As for “stripped from” vs. “hidden within”…in the strictest sense, the answer is, “neither”. The form released by Yang Cheng-fu to the public neither had all the martial applications stripped from it nor hidden within it. It quite simply wasn’t the martial form. It was the Yang family qigong form and represented the Yin side of the art as regards qigong. The martial form was not released to the public at that time, even by Cheng-fu. The Cheng-fu form (what most of the world thinks of when they hear the words Taijiquan) does have SOME of Yang Taiji’s martial applications hidden within it, however. And at more than one level, it might be noted.
Traditionally, the rule of thumb for neijia arts is that the postures in the forms contain at least three applications apiece, representing expression at the “obvious” (representing large frame, open gate techniques), “hidden” (representing medium and small frame techniques, true internal structure and use of proper jings), and “mysterious” (representing small frame techniques, internal structure, use of jings, implementation of Dim-Mak striking, and use of intent to direct adverse qi) levels of power. Quite ofen there are more than three applications, but there are usually at least these three. It must be noted that the Yang Cheng-fu form’s postures contain all of the first level, much of the second, and very little at all of the third level of power. Again, the reason is simply that this was not meant to be the combat form (which DOES contain all of the third level), but rather the family’s personal qigong form for health.
As for Baguazhang, you are a bit in error here. The style is no more application oriented than Taiji is. Put perhaps more clearly, Taiji is no LESS application oriented than Baguazhang is. Original Yang Lu-chan (not Cheng-fu) Taijiquan is chock full of devastating, brutal and often deadly applications. It’s one of the biggest ironies in the martial arts that, today, Taiji is considered perhaps the softest, least violent martial art out there, when the truth of the matter is almost nearly the reverse.
As for training in both Bagua and Taiji for dual perspective on the same problem, I say go for it. It won’t be the easiest undertaking you’ll ever do, but the rewards should be deep, rich and constant. Best of luck to you…you sound like a dedicated and attentive student. 
