mining pos in active? %?
About 3% a year. If you stake constantly, you will get slightly more than 3% from capturing transfer fees.
and to stake every week... how many coins i need?
Any number of coins will make you eligible to stake as long as you keep your wallet online at all times. 100k coins should predictably stake every week. 10M will insure that you stake a handful of times a week. Your coins accumulate 'weight' the longer they go without signing a block(staking) so even just 10 coins will stake eventually, but it may take a bit of patience.
to mining in pos i need to download
Windows Pandabank 3.0.5.3
right?