I haven't updated to 2018 yet so I can't say anything about #1.
But I 100% agree with your point about automatically setting the default mapping to world scale. I would also prefer if you could set the default mapping technique to box or whatever.
I am sooooo tired of having to set these settings manually for every. single. part. every. time. It eats up so much of my time. If the model is imported with appearance grouping at least it's manageable setting them manually. But when importing animations and you get upwards of thousands of parts... Forget it.
IF an imported part already had a texture assigned in SW, then use UV mapping and use the imported texture - like Visualize does today.
But for all parts with a color assigned -> use the user's default mapping and scale.
I brought up the request about having user defined default mapping techniques and scale as early as the first Visualize BETA. :/
1. is working for me fine even without using offline rendering so It could be something with your install, drivers etc i would collect logs and submit to your VAR for investigation
2. Copy and paste again works for me in 2018 SP1 either via Shift+ LMB and Shift +RMB or the right click menus copy appearance and assign copied appearance
so for those I think it may just be you. as for the world scale, it would definitely be nice to have that, perhaps as an option that the user can set whether to scale or not.