[paktek123]

It is a tough spot to be in. I think you are quick to identify the skills gap. It might be worth raising this issue with management and see if they can hire a senior dev. If not then I'd say clarify your skill set to management and say you might need some time to do reading and get your skills up to scratch. If no cooperation from management then screw it, go with flow and give it your best shot.

[melonbar]

This. I currently was given a lot of responsibility in a short amount of time (I am a software lead developing isomorphic SPAs) despite the fact that I am far from a senior dev. Sometimes companies just need people to step up. It could be a boon or a disaster but the best you can do is make the situation clear to management and just keep doing your best. Sounds kind of cheesy but honestly this could be an answer to all of those questions. Sometimes you just have to do the best you can, focus on the task at hand, and if that is not enough then que sera sera.