DSS and renting a house

Hi.

I find this whole DSS stuff a bit confusing, even after using their calculator.

I'm thinking of rather than waiting to get a job in Manchester, finding somewhere that is ok with DSS, and claiming DSS whilst I find a job which hopefully should not be too long.

If I for example found somewhere to live in Manchester in 2 weeks, and moved in, then using my savings to live, and I contacted the job center and applied for DSS -

How long would it take to get the DSS payments?
Do they get back dated from the day I start to pay rent?
I assume there is a limit, is it around £60 per week, so if I was renting at £90 per week the rest would come out of my pocket?
With DSS comes JSA, do you have to be on JSA to claim DSS?

I'm just trying to weigh up if it's feasible and "safe" for me to do it.

Thanks.