Trading on Margin

[ep510]

I'm interested in trading on margin, but have a few questions regarding the process:

1. Are interest payments automatically deducted from my account whenever I sell?
2. If the margin rate is 10.5%, is that rate compounded continuously? Daily? What is the equivalent rate on a daily basis? Can you please explain how that works?
3. If maintenance requirement is 50% and maintenance excess equals total equity minus maintenance requirement, then shouldn’t:
- Maintenance excess be equal to the value of maintenance requirement
- Maintenance excess should be equal to 50% of total equity as well
4. If the maintenance requirement is 50%, am I correct that my maximum buying power (before a margin call) should be two times my total equity?
5. How do I interpret my cash balance and market value of my portfolio including shorts? It seems that cash balance – market value = total equity. But when I short a stock, my cash balance increases while my market value decreases. Am I right to assume that when I short a stock, I automatically am trading on margin (i.e. even if I have not surpassed my total equity in purchases, I will automatically borrow money from Zecco?)

I would greatly appreciate any answers to the above questions.

Thanks,
Eric