I would suggest an
ECV over a wc for several reasons.
The most important of all is that it will give you more freedom than a wc. If not used to a wc there will be lots of exertion on your arms, which are not used to it. Also it is difficult for people not used to pushing, especially where there are hills or rough streets which would otherwise not be noticed.
Also, there is a pretty large amount of storage available; At least the ones from Walker have a pouch on the back of the seat as well as a basket in front. The floorboard is quite large and depending on how you can move your legs you can keep a few bags on the floor, and it is also possible to hang bags from the handlebars (but be VERY CAREFUL that you do not interfere with the controls).
From you latest post it seems there will be others besides you and your GD; let them worry about the stroller and her.
Two other things -- when using the bus, it may be easier when once on the bus if you sit in a regular seat. Also, if you are the only ECV on the bus you should have enough room to turn the ECV around so you can go off to the front.
Most important for safety. Do not allow your GD to ride on your lap and "help drive". If she jams the control you can run into people or things, which is very hazardous for all concerned.