中銀 provides you a very safe platform (you know, security firm is dangerous!). Many ways you can buy shares, e.g. net, phone and branches. Fee is fair. 0.25% when using phone and branches. Only 0.15% when using net.
But you need to pay deposit fee (about $5; $2 using net) for each lot. Also, sometimes the phone is not through, particularly the opening hour and closing hour.
Hope that can help
1) Min. commission is $80 (or 0.262% all-in fee plus the deposit fee via the net)
2) No deposit fee on selling; other fee is same as above
3) Yes, Deposit fee = 存倉費 ; You can send the buy/sell order at different spread (i.e.掛價 )
I think using 中銀 to buy shares is good, but don't buy warrant/small price stock as the deposit fee would be huge.