Running PortableApps.com Platform from a Read-Only drive

I am thinking of switching to the Platform proper. Currently, I download and install each PortableApps.com application individually. I am looking to solve two wishes by switching to the full platform.

First, I wish to install to a USB flash drive and then run applications on other computers with that flash drive set to read-only. It's okay if a few applications don't work like this, but does anyone have experience trying this? Does it just give too many issues in day-to-day usage? Currently, I have two sets of apps, one I use on my own system, installed to the hard drive, and another on a flash drive which I use on untrusted systems. (Side question: Does the read-only switch on a flash drive prevent writes via hardware, or is it just a flag to be read by the OS and then the OS mounts the drive as read-only?)

Second minor wish, I want to have file associations on the go. I understand the official solution to this is being worked on. The links I found in the forums to previous unofficial solutions are all dead links now. And it is my understanding those will not work on Windows 8 and newer. Xenon is what I have used for the last year, but sometimes an application just doesn't work for you, if you know what I mean. Mostly I need to associate archives like .ZIP files, and starting 7-Zip versus starting Xenon is the same amount of work. It's possible I missed a thread. If there's something obvious I should read, please let me know. Thanks.