Can I import work items and stream history from a 3.0.1 installation to a new standalone 5.0.1 version?

There is, so far, no built in capability to migrate the data. This is a popular request, however.

Work Items - the easiest approach is using CSV export/import. Unfortunately CSV is a horrible format for doing this. You would, for example, have to go through the data and remove line breaks e.g. from description fields. There is also more work involved if you want to link the work items up.

SCM - you can use distributed SCM ( https://jazz.net/library/article/535 , https://jazz.net/library/article/1399 ) allows to transfer streams with history, but there is manual work to accept all baselines and you loose the snapshots (or have to recreate them). The systems also must be on compatible versions, which means you have to upgrade the old server to 5.x.

Several users have written tools to help with this (including Sam). There might be a service offering to help with this, however it will likely require to upgrade the old server to a compatible version, too.