I have tried to gather some important ones. I will update this post when I spot something new :)

Developing

1. 3 - devices can be unlocked by one developer(one live ID)
2. 3 - apps can be deployed by DearmSpark developer per one phone
3. 5 - free apps per account (next one is 19.99$)
4. 5 - seconds after launch the app must show something to the user(loading screen f.e.).
5. 10 - apps can be deployed by developer(paid fee) per one phone
6. 15 - push notification channels per device
7. 20 MB - The maximum size of the OTA (over the air) installation file for the application.
8. 30 - frames per seconds XNA updates the screen.
9. 60 - frames per second Silverlight updates the screen
10. 62 x 62 - icon size(PNG)
11. 90 MB - memory usage for devices with 256 MB ( limit can go up for devices with more than 256MB)
12. 99  x 99 - Small mobile app tile (PNG)
13. 173 x 173 - tile size(PNG)
14. 200 x 200 - Large PC app tile(PNG)
15. 225 MB - The maximum size of the XAP package file.
16. 480 x 800 - screenshoot of an app.
17. 1000 x 800 - Panaroama background for marketplace - not 1440 (PNG)

Money

1. 0.99$ - mimimum price of an app
2. 99$ - registration fee
3. 200$ - payout threshold
4. 499.99$ - maximum price of an app

The collection time of payment

1. 15 to 30 days for credit card billing
2. 90 to 120 days for mobile operator billing