DLA won't automatically stop if you fail your ESA medical, however the results of it can be used if the DWP chooses to review your DLA entitlement.
If you are currently on IB, you will be able to claim ESA(CB), but as you will have read elsewhere on this site, the government is trying to get legislation through that will limit this to one year for people in the WRAG (but not for people in the support group) after which it would be means-tested.
If you fail to get ESA, you could apply for JSA. We don't advise on JSA on here. Normally, JSA is paid on a contributions-based basis for six months, and after that is income-based. However, whether you would transfer onto JSA(CB) from IB if you don't get ESA, I couldn't advise.