It depends on what coin you choose and how good you analyze the coin movements. As long as you can pick the right coin and you have the skill to enter and leave the market, then I am sure you can make 10% a week and even more. Right now, you need to be careful when you want to choose the coin because you don't want to wait too long to see the coin price can increase. But perhaps, you can use bitcoin only than the altcoin because, with bitcoin, the differences of the price can help you to gain a profit, but of course, when the price is down, you will see it drops too deep.
I would rather suggest not to look for more coin options than to settle in BTC/USD pairs. Since the time-frame is one week.
It's best to wait for certain shifts in movements and then move ahead.
For 10% you need to have enough money and skills in order to achieve, with the small investment it is impossible to make 10% profit on a weekly basis. I hope due to market fluctuation it is also impossible to make a decent and right profit and sometimes you may even make more than 10% or even you may make less than 10% too.
Not that much. A person with a basic knowledge of trading can easily achieve 10-15% within a week or two probably.