Don't quite understand SQL Server transaction logs

Question

I've read up on SQL Server transaction logs, but still not entirely comfortable with how to use/manage them. I get that they are important for things like transaction rollbacks, mirroring, replication and log shipping etc.

To me, they still seem like a black box and I'm not entirely comfortable doing anything with them. Are there tools that allow me to view a transaction log file or get information about it? If I don't need things like transaction log shipping, is it ok for me to shrink and/or truncate my log files periodically? Particularly in the case of restoring backups onto a test instance - do I really need a multi-gigabyte log file taking up space? What other features do I need to be aware of that have particular dependency on transaction logs and would not work if I shrank/truncated log files?