Since the rules only came into effect 1st March 2019, nobody really knows yet. The educated guess is that they will check at your next application for extension.
Lastly, the re-entry permit will only let you return and stay up to the current admitted to stay date, no longer. If you wish to stay longer but not work, you could use tourist visas or visa exemptions.
If your new employer is not ready by then, and you qualify for a visa exemption, you can do a border bounce and get potentially 60 days more for your employer to finish whatever they need. You are not allowed to start work with the new employer until the new WP is done anyway.
Hotels and guest houses would have the online system set up if they are properly managed. As for friends’ houses, the reporting limit is 24 hours, so I’m guessing that if you don’t stay more than a night, you (or your friend, rather) might risk not doing the TM30.