Website, DB, & Software Developers

SQLite is a file manager like Access. They both have a high potential for corruption especially in a multi-user configuration since the updates are not purely transactional. Only one connection may write to the database at a time. Direct from the Sqlite.org site: "A good rule of thumb is that you should avoid using SQLite in situations where the same database will be accessed simultaneously from many computers over a network filesystem."

MySQL is a much better option, but I understand your hesitations since most of the documentation expects that you already have familiarity with an RDBMS. I'm not sure if you've looked into MS SQL Server.. It has, by far the most "Google-support" available of all the mainstream RDB options. And, SQL Server does have a free version, MS SQL Server Express Edition which only has a limitation of 10 GB max data size (transaction logs are not counted in this limit). It doesn't sound like you would come very close to that limit in a long, long, time.
https://www.microsoft.com/en-us/sqlserver/editions/2012-editions/express.aspx

To manage the SQL Database, Microsoft also offers a free version of SQL Server Management Studio
SQL Server 2008 Management Studio Express - http://www.microsoft.com/en-us/download/details.aspx?id=7593

Here is a pretty good article that explains how to connect your PHP app to the SQL DB and perform your CRUD operations:
http://technet.microsoft.com/en-us/library/cc793139%28v=sql.90%29.aspx

Hope this helps.