1) Strict airport regulation of traffic/surface movement radar/unambiguous signage and crew training to list a few of the 'precautions'. However, if someone by mistake drives a fuel tanker across a foggy runway in front of a high-speed metal tube, there will be a big bang. The 'separation' on approach is to avoid disruption of the ILS signal, not the 'collision risk'.
2) I would say yes, absolutely.
EDIT : Just read your query properly!
I suspect ALL pilots will at some stage carry out at least one RTO, but the high-speed case less likely.