Assumption Rule in Dependent Type Theories


I am reading an introductory book on type theory and formal proof, I get confused with the assumption rule:

If $ \Gamma\vdash A: Type$ and if $ x\not\in FV(\Gamma)$ , then $ \Gamma, x:A\vdash x:A$ .

My questions are:

(1) If $ y:A\rightarrow\perp$ is an assumption in $ \Gamma$ , then does $ \Gamma$ derives $ A:Type$ ?

(2) If (1) is the case, shall we extend $ \Gamma$ with the new assumption $ x: A$ ?

I think there must be some clearer explanation for the conditions of application of the assumption rule, but it is at least not clear from the introductory book I am reading. Thanks!