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That is quite an old version. I would try doing the upgrade steps locally on a test site first. That will give you the answer for sure regarding the theme and modules.
In the latest version there are release notes that give step-by-step instructions for the upgrade.
Use the checksum files to make sure you have everything uploaded properly before attempting the upgrade.
If you list the modules you are wondering about, someone may be able to better advise you what is likely to work or not.
Optimism is the mother of disappointment.