It depends on how dependent you are on the foot orthotics. If the original problem that they were made for has settled, then you can start spending more time not using the foot orthotics as long as this is done slowly and progressively and you adapt to it.

I not familiar with those flip flops (or thongs as the Aussies call them). There are others around that look similar. They could be OK to use in limited amounts, especially if you live in a warmer climate.

Archies!!! I can help you there as we sell them in our clinic:
https://croydonfoot.com/archies-thongs-stockist-melbourne/
and I wrote about the Aussie slang of 'flip flops' vs 'thongs':
http://craigbpayne.info/thongs-only-in-australia/

and I also made this video on how I go about modifying them to better some feet in some people:
http://www.podiatrysoapbox.com/the-archies-mosi/

I like them. Pretty much anyone who tries on a pair buys them.