WACC weights tax shield and CAPM rates help

Hey guys, just writing this at 3 AM with panic setting in trying to finish chapter 4 of the Corporate Finance module. I am seriously stuck on how to figure out the WACC when a company has both fixed and floating rate debt but the exam question doesn't specify the weights clearly. My brain is empty and I keep messing up the cost of debt calculation because I miss the tax shield part or apply the wrong interest rate to the equity portion. Is there a simple rule to remember for assigning the weights for the debt versus the equity part when the market values are not given? I feel like I have wasted an hour on this one paragraph when I should be moving on to the dividend policy section. Also, I need to clarify something about the Hurdle Rate rules versus CAPM. The text says we calculate the cost of equity first then use that to find the hurdle rate, but some questions in the exam bank seem to ask for the discount rate directly from the CAPM formula using the ungeared beta. Finally, can someone tell me if I really need to memorize the dividend irrelevance theorem for the CME-1 paper or was that all just for ICWIM? My study plan is a mess and I want to make sure I'm not wasting time on irrelevant theory while the Corporate Finance section is piling up. Thanks in advance.