I’d say that you can stay on 32 bit, until you know you need 64 bit.
Here’s a blog post from Scot Hanselman showing memory usage decrease between 32 bit and 64 bit: Penny Pinching in the Cloud: Your web app doesn’t need 64-bit - Scott Hanselman’s Blog
When it comes to databases, I’d highly recommend looking into DTU based SQL Elastic Pools in Azure. They’re priced well and allow for multiple dbs on a “server” with overlapping DTU usage as well as per database DTU limits.