Thanks.
1, The open crossfeed valves may have been an inadvertent error on my part . I noticed when I closed them on the flight I am conducting now the error has resolved.
2. Yes on downloading en-route weather to FMC.
3. Fuel calculations have been calculated as mentioned and I have landed with plenty of reserve still showing a fuel warning . Oddly this has only just started happening over the last 4 flights.
$. Yes I let the FMC calculate my step climbs.