Current consumption by a LDO (5v to 3.3v)

You don't want a switcher. Your input-output difference is so low (for most of the discharge curve the voltage is less than 3.8 V) that even at 90 % efficiency it won't do better much than an LDO.

Have a look at the Seiko S1167:

• Ground current typical 9 µA
• Available in 100 mV steps from 1.5 V to 5.5 V
• 1 % output voltage accuracy
• 150 mA output current
• 150 mV drop-out at 100 mA
• Shutdown input
• SOT23-5 package

edit
Found an even better one in the S1313:

• Ground current 0.9 µA
• 200 mA output current

Seiko doesn't give data for ground current under load, but in my experience you should count on 1 % of load current, so at 1 mA that would be around 10 µA, most likely less than 50 µA.

Yes, you have it correct in the two equations for total power consumed from the battery.

There's typicals and maximums which are a bit higher than the typicals for Iq and a bit lower for efficiency, of course, and the efficiency could vary if you use a different inductor or other conditions vary.