They are really simple to setup. There's 3 lines- red, blue, and black. The red goes to your faucet or spigot, the black goes down the drain, and the blue is your filtered water. I got one of these units when I first started out, send them a message and tell them you need both adapters. Otherwise, they will just pick one and send it too you.
As far as water pressure, are you on city water or a well? If you are on city, you will most likely have enough pressure, if you are on a well, you may need a booster pump, it all depends. If you have less pressure in your bathroom than your kitchen, then unscrew the little screen on your bathroom faucet output, it may just need to be cleaned.
As far as running off of a hose, personally I've never tried. Hoses can have some weird chemicals in them, but you could thread the hose adapter to an outside spigot.
Once it's hooked up, don't plan on a RODI
filter making water faster than you can collect it, these things are slow and it takes time.
Hope this helps!