2. The situation you're talking about has existed since... well, it's been there for the last 3 years I've been using Google Calendar. I, too, would like a working back button, but the web UI is effectively set in stone.
Love google calendar for the cloud, sharing and ability to email myself custom reminders but the UI on the web is pretty minimal. I tried a couple different calendar apps and found fantastical by flexbits.com to have the best UI/functionality for me on iPhone.
I have my custom view set to 3 weeks - but the same principle - it shows me from today (or rather, the Monday of the week that today is part of) through to Monday 3 weeks away. It cares not a jot for where I am within the month. Setting the custom view to any other numbers of weeks will doubtless provide the same 'sliding x-week window' view.
It gives an x week window offset by n*x weeks.
So you can see now through 3 weeks, and 3 weeks through 6 weeks. But I want to see 3-4 weeks of window and slide by one week!