The current version is right now indeed 2.1.1547 and is the one available at https://www.axcrypt.net .
You should not see any incompatibilities in any case. We are always downwards compatible, i.e. newer versions always work with older encrypted files.
No special steps required – but do reboot if/when asked to.
Your files remain encrypted regardless of the install-state of AxCrypt.
Your files remain encrypted with the same password regardless of the install-state of AxCrypt or if you re-install.