Great advise from everyone,

The closer you play to the bridge, the more pressure you must apply as Daniel said. Playing closer to the bridge will enable you to miss the other strings easier. You need real precision to miss the strings on both sides. Usually comes automatically with time. Practice a D major scale on the D-string only looking at the bow contact while doing so. If you feel brave you can stretch the 4th finger to hit the octave D. Play the scale every so often to establish the proper angle to avoid the other strings. It seems as though you are moving along very ambitiously by playing positions in your 3rd week.

As far as the bridge being soft, most professional violinists have a parchment (drum-skin for example) glued on the bridge under the E-string so that it won't cut through too much. My luthier inserted bone in the bridge under the E string.
I don't think that you need to worry about that for the moment.