You probably don't need to do a flush if you've been using M1 and changing regularly. It sounds like you have a pretty good plan if you decided to go that route.
As far as oil consumption, M1 is thinner at temperature than many 5w30's. Your oil consumption might be normal for this oil. If you want to reduce oil consumption, you may need to selecte a 5w30 or 10w30 with higher viscosity (see product spec sheets or the virgin analisys on this site). Or if you are the experimenting type, you can try the 0w40 Mobil 1 and probably get rid of oil burning, but do this only if you feel comfortable using something that isn't recommended in your owners manual.
As far as oil consumption, M1 is thinner at temperature than many 5w30's. Your oil consumption might be normal for this oil. If you want to reduce oil consumption, you may need to selecte a 5w30 or 10w30 with higher viscosity (see product spec sheets or the virgin analisys on this site). Or if you are the experimenting type, you can try the 0w40 Mobil 1 and probably get rid of oil burning, but do this only if you feel comfortable using something that isn't recommended in your owners manual.