Crossfit

I don't know but I would say close to 600 you will get strong fast with this program. If it turns out to be too hard go to crossfire lite or a general foundation program with kettle bells. You will see results fast

If you want more than an estimate, try using a HRM to log your calories. And don't forget to adjust your weight in the HRM's profile as you lose weight.

Using a Garmin HRM to measure I usually get about 800cal per training hour in cf. Hope ir helps

This is my personal opinion, i do not know if it is right or wrong,.

In my opinion you cannot use any equivalent to log your crossfit. There will be a 50/50 chance it may be right or wrong and this is because you get a WOD each day and each WOD will burn different amount of calories. The WOD (this link gives an idea of how different the WOD's can be http://www.woddrive.com/list-of-wods.html) You can burn 300 today, 600 tomorrow WOD etc.

In my opinion, your best bet if you want something more realistic will be to get a heart rate monitor as the others have suggested and get an idea of what you burn for each WOD. You only have to do it once for that WOD and you can use it as a bench mark the next time you do that exact same WOD and either increas or decrease based on if you scale up or down.

Goodluck, crossfit is fun