Me too - would be an interesting one as I don't know if just changing the item level would also change the associated stats? Unsure if it's calculated based on the existing stats.
Great reaction times from CH as always, thank you!
It's fixed in next trainer update, which will be posted soon.
It will if you are the host, if you are a client then the trainer will likely not work. I would suggest not using it in a MP session unless you are playing with friends that want the effects of the trainer. Otherwise you could ruin the experience for other people if you accidentally max out their skill points or something like that.