Apparently package fees are still only applying to convention resorts (where they have for a long time) and the new $5 fee at the value resorts. Other resorts do not appear to have the new fee, at least yet. The "shipping to resorts" thread has posts as late as mid January confirming this, so it is possible it has changed since.
Direct *deliveries* however, such as a medical supply company might make directly to a resort (as opposed to FedEx, UPS, USPS), did not appear to incur the $5 fee at the values (and I don't think they do at the convention resorts). For example, Garden Grocer deliveries do not incur the fee.
OP: your airline will have information on traveling with medical supplies/equipment/medication on their website. They should also have a number you can call for disability assistance to talk with them about your needs and clarify their policies. Medical equipment won't count towards your baggage allowances, the challenge will be how to transport it safely and to meet airline requirements for some of it (eg if there are batteries, or oxygen there are special rules both by the government and the airline).
I encourage you to print a copy of what they have on their website, as well as get as much of the discussion you have with the airline in writing if you can. I recently had a not so great experience traveling with medical items -- three airline employees did NOT follow their policy and I ended up having to airplane-door-check one carry-on (when I should not have had to at all). I complained to the airline during travel (long layovers and a smartphone with facebook are useful tools) and they both confirmed I was correct and apologized, promising to retrain the employees. I don't know if having had a printout of the polocy from the airline website would have helped me or not, but it would have been better than me trying to verbally explain to them their own policy that they insisted was not correct and that "optics" overruled disability accommodation.... :-( I have flown many times and not experienced that before, so am hoping it was an exceptional event. But next time I am coming prepared with printout
If you expect to have items shipped or delivered to your resort, contacting Disney for information will be helpful. Getting an answer in writing is always useful too, especially if they say there will be no fees and you then get charged a fee.
Good luck and enjoy your trip !
SW