SQL Server Express

"How easy is it to schedule backup and other tasks? I know it's all doable, but is it more of a pain?"

Nope, pretty easy actually, you can use ExpressMaint.exe for SQL Express backups and maintenance: http://expressmaint.codeplex.com/

And as Siim K and Nick said, as far as the stress and load on SQL Express, out of those 50k hits, how many of those hits do you think are requesting data, or writing data to the DBs? If it's only a section or two of the site, I think you would be fine, but if the site is heavy on DB calls, then you are going to need to look at expanded options.

You can either write something manually in t-sql using BACKUP DATABASE, then schedule it to run using the windows task scheduler and SQLCMD.

If you're not that way inclined there are several people who have written apps such as SQL Scheduler that give you nice GUI front-ends.

Is SQL Express good enough? You're the best person to answer that question. It depends on what your site is doing, how database intense it is & how big the database is.