A few additional things I suggest from experience:
1. Make sure the bolts have washers under the heads. When you tighten the bolt the washer should remain stationary so the bolt torque is less likely to 'twist' the caliper.
2. If you still get movement when tightening check that the caliper mounting faces (top of the posts) are flat. Sometimes you get a paint build up on the top of the post on some frames. The caliper will 'tilt' slightly as the bolts tighten rather than 'twist' in this is the case which causes the pads to be misaligned radially (rather than circumferentially). In this case you need to carefully scrape the paint off the top off the posts.
3. You should have a pad spacing tool (usually red plastic) to insert between the pads when the wheel is removed. This is useful for setting the pads spacing. Often you will need to open the filling port in the lever when using this tool to set the pad spacing. If you do have too much oil in the system the excess will come back out through the filling port.