Hi,
I have read you details, and I would like to recommend something to you related to it.
Firstly Apps and website are two separate things and your requirements are huge so I suggest, First make a website, then just put the website in the app, When someone open the app it will show the website and things will go smoother, through this way I guess, you have have your project done, Infact in this procedure too, you will have to spent more money as well because APPS costs are much more then website designing
Looking forward to hearing from you, to share more details and provide you an offer.
Regards