2) What Icarus said is right, however if the MSA is say 5000', your LSALT is 4000' and once you pass over the aid you're able (on the chart) to descend to say 3000' on the outbound leg before becoming established inbound, then I'm not aware on any reason why you couldn't start the approach from a lower altitude. This is of course provided you are at least on a heading to intercept the outbound track once passing overhead the aid. Remember the approach is designed to 'get you visual' with respect for limiting safe altitudes. As long as you are above a published minimum safe altitude at all times then it's ok.
It would then be a question of why or if you should descent to the LSALT prior to starting approach and would be dependent on the variables involved with becoming visual. These would obviously vary with runway in use, the aerodrome itself with respect to the approach and prevailing weather conditions.