There are quite a few posts on here about transitioning to live trading but I still have a few questions before I start paying for a server. 

1st- If I would like to edit a parameter such as a sell point, is there a way to do so without liquidating the current held assets? Can changes be made without fully killing the algorithm?

2nd- When using the universe selector, will the coarse selection function run upon start up or will it run at 16:00 as they do in backtesting? I'm trying to make sure the first day does not consist of waiting until after the trading day to build a coarse universe and then begining trading on day 2.

3rd- When getting tick data, what do the letters of the different exchanges data comes from stand for(N,D,T,X+ some others) and should the algorithm ignore tick data from all but NYSE (I'm assuming N stands for NYSE or NASDAQ)?