Mittleider gardening down under

Well I'm all, well not exactly fired up, but determined to get set up
the Mittleider way soon. Of course downunder we are coming to the
tail end of summer and too soon into winter. So I have a few
questions. First of all I have an area that will get lots of
sunlight, soon as I lop a few real ugly trees down. But it is in
grass and there are a lot of vine type plants which go under the soil
and poke their way up. So what is the best way of tackling these two
issues? One thing I am unable to do is to dig into the ground with a
grubber as I have injuries which limit me in such vigorous
activities. Obviously I don't want grass or vines growing up through
the media.

For the frames I am going to have to use treated wood as
most wood native to New Zealand is not hardy to rot, so I know I am
going to have to paint them with acrylic paint. However I am
concerned that the ends will pull away from nails over time. Should I
used coach bolts to screw them tightly together?

And finally, my wife loves strawberries. And we have never been able
to grow a good crop for a host of reasons. So I bought a strawberry
planter which is plastic and barrel shaped. What would be a good
media to use, should I put in a drilled pipe to water it or should I
just use a drip irrigator to keep it continually moist?