Regarding hiking togeher or not, well, that's just the thing.

If I'm with someone I generally do either two modes of operation

1) (and this is always the case with someone new, or new to me) Stay in sight of each other.. always.

2) Be packed independantly, walk independantly, but have a plan. essentially this is two solo trips. I will do this with people I know. and then it's agreed ahead of time with agreement of "I will probably end my day either here or here." Typically in this case we are camping in the same spots - and part of the "plan" is the knowledge of "I am not going to worry about you at all today, unless you don't show up in the place we have agreed upon". The assumption here on both parties is that we will look for the other one if they are overdue, and we *better show up* where we agreed upon or we're giving the other person cause to be concerned.