Hey welcome back. Has been a long while since I thought about visas, but pretty sure the wording is that "PR visas don't expire, only the part that allows you to travel into Australia does". Hence you can be in Australia as a PR 'forever' without needing a visa or to become a citizen. However if you want to travel you need a new visa -- this is where the RRV comes in. From past posts, immigration can be quite generous with RRVs i.e. if this your first time of asking for one they will likely grant you one and getting a job offer would be sign of a commitment to Australia (which is one of the criteria).
Not sure how true it is, but was often said that applying for an evisitor/visitor visa is a terrible idea, as the risk is your overwrite your PR status and are left in a worse state than before you started.
Is prolly worth getting some agent advice, to not stuff it up.