Sorry I got lost now...Why voting might be considered not secure? The way I do it is I vote for people I know (c50 - 70 delegates I think) and which is below 101 since many of the delegates I don't know who they are. Also some of the delegates I vote are not on the 101. Then I press the button "vote all".
All you say is correct
Since I am not voting for 101 I have the message that I am not voting with my whole balance. Is this a risk? Should I vote at least 101 even if it is people I don't know?
It's just a information that you are not "using" your full voting "power" ... which you would if you voted for >101 delegates
Do I correctly press "vote all"?
All fine! if you go to your transaction history you will certainly see a transaction moving ALL your stake in the account from which you are voting .. that means you successfully votes ... the "vote now" button is doing nothing more than move ALL your funds back to yourself
Should I vote and press that button everytime I make a transaction or I can just do it once and it is ok?
Voting happens automatically when you do ANY transaction on the network in BTS ..
if you changed something in your prefered delegate set .. than you should revote with all your stake .. i.e. press the "vote now" button
P.S. Voting is complicated I think..
I tried to summaries something over in the wiki:http://wiki.bitshares.org/index.php/DPOS/ApprovalVoting