Spreads are floating and follow the underlying market. Commission is charged per lot on some instruments and varies by asset class. Exact conditions for each instrument are visible in the terminal before you open a position.
All daily limits, resets and Friday closures run on server time. Your dashboard displays the current server time.
By email, immediately after purchase. Check your spam folder if it hasn't arrived within a few minutes.
Platform 5 and Match-Trader. You choose your platform at purchase.