Ok I will try to give you some answers (for what I know)
1)It might take from few months to years, depending on availability, transfer rate, people leaving/retiring, company requirements etc. For some people it took a year, some others had to wait 5/6 years. They open the list every 2 years and it's done strictly on seniority. Some ppl last year though were recruited for LGW LH. Nothing can be predicted in BA!
2) BA, no doubt. Had an offer from VS myself years ago, but didn't accept it. I guess it depends what you want to do, really. If what you are looking for is long haul straight away, then maybe VS. I chose BA for the different kind of environment at work, the responsibilities and many other reasons. BA is such a huge company you can spend your whole life there and do lots of different jobs other than flying. But yet, this is only my personal experience/opinion.
3) I don't know much about it, but if I am not wrong they pay crew allowances when you land at a destination. Crews tend to spend it while they're overseas. That's money you don't get at the end of the month! Maybe a VS crew can give you more precise and detailed info.
4) Cannot answer, I don't know.
5)NO, that is wrong. In the last 2 years they've been recruiting for WW LGW, EF LGW and EF LHR. They even recruited directly for WW LHR at one point, until unions kicked off (with good reason!).
At the moment they're recruiting for EF LHR. Check the website for up-to-date news, it tends to change almost every day!!!
I hope I have been of any help. If you look into the main BA thread you'll find TONS of info, which will hopefully help you make a decision
Good luck!!
FBW
***Love at first Flight***