Don't forget you can also install Amicygnix which will let you run Abiword and Gnumeric under OS 4.1. Both of those are pretty good packages and have reasonable Word and Excel compatibility - far more than Wordworth anyway. There's also a port of Gimp for Amicygnix for graphics work.
Doing web development really depends on what you're doing. For palette-based graphics (GIFs etc.), PersonalPaint is excellent, and I still use it for some things that are just simpler to do there than in Fireworks etc. Text editors aren't a problem, neither are FTP clients. For prototyping websites there's a port of AMP (Apache/MySQL/PHP) so you can run a local webserver, and Amaya is a WYSIWYG webpage editor that also has a port for Amicygnix.
Email is reasonably well catered for with YAM and SimpleMail. YAM is more feature-laden, but doesn't support IMAP or HTML mail preview (though it can send them to a browser for viewing). SimpleMail does support IMAP and also has all the main features you'd expect from an email client.
At the end of the day, all the things you mention are possible on OS4.1, though there will be limitations of course and in most cases things would be easier using Windows or a Mac. Amicygnix in particular is slow enough to be frustrating unless you've a fast machine. Let us know how you get on anyway.