The other desirable features you could mention, for example, an encrypted data transmission via SSL or a WebDAV access or powerful software which goes beyond the usual home-kits, for example, a professional website editor, how to offer him 1 & 1 with Dreamweaver – but these are an older version. And CGI libraries, cron jobs (which you can set up automated actions) and newsletter tools. 1 & 1 offers it in its higher-priced offers an impressive feature-richness.
In general, relatively easy to get to at least PHP and a MySQL database, Python contrast or SSH access are less common and included only in higher-priced fares. The same is true for cronjobs and SSL certificates. If you prefer scripting and database solutions from Microsoft instead of the proven and widely used combination of Linux, PHP and MySQL, you should also look for something. 1 & 1 offers as mentioned in such Windows-offers, but this cost is compared to Linux/Open Source-based hosting offers much more.
If you’re thinking, appearing as a hoster, you should clarify if your desired web hosting reseller deals holds as it does, for example, 1 & 1. Clarify for your safety, whether you are allowed to use hosting packages for residential customers for commercial websites (usually is the case).