Sadly the only way around this is to get on a licensed server, where people have a reputation to uphold and autocross objects can be used, just as Dalek said. On the CTRA servers you can also get penalised for cutting.
To answer your question, madbikes, you weren't wrong - they were, but as said before, there's hardly anything you can do about it in the demo
Only if you're one of those ABS-spoiled persons. Most of the cars I ever drove didn't have ABS, and I personally never needed it.
I tried LFB in real life too, but it's quite useless, because you still have to shift sometimes - which is preferrably done with the clutch. Heel-Toe works quite fine and I regularly use it on road cars, most likely because I like the revs to match the new gear
In LFS however I was LFBing quite some time too, but I almost completely stopped it when I started using a clutch pedal, for the same reasons as above
My upload is 8kB/s. I wouldn't want to send skins while racing. I would however like to see a "send skin"-button, just like "send setup", but I think that also was suggested before.