When people talk about the 'clearance' of an antenna, they seem to
mean how high the antenna is suspended above the earth and surrounding
objects. It also seems to be agreed that, at least with most types of
antennas, the more clearance you have, the better.

If I were going to put a random wire antenna on the roof of my five
story building, would the elevation resulting from its rooftop
location be a plus even it's only six or seven feet above the rooftop
itself (assuming there's not a lot of rfi up there from power lines,
the apartments below, etc.)?

Second question: I'm thinking the random wire should attach to a balun
which should then attach to a coax feedline. (My understanding is
that, if the wire isn't cut for a particular band, I'll need to use
either a balun or a tuner-- and it would be nice to avoid having to
fiddle with a tuner all the time.) But how does one determine what
sort of balun to use? For example, how does one decide whether to use
a 4:1 vs a 9:1 balun? Can anyone recommend a particular balun that
they've found to work well with a random wire antenna?

Thanks,

Steve