Investment appraisal

Investment appraisal
Dear Sir,
I have some questions for you and I hope you can help me.

1) Tax allowable depreciation (actually this is not a question, but mainly a confirmation of my understanding)
unless we are told otherwise in the exam we should assume that an assets is purchased on the first day of an accounting period (T0) and that the first tax calculation start on 31 december T1 (so if they say that tax is paid 12 months after the end of the year, cash inpact will be in T2 ). But if they say that we are on 31 december (so T0) and tax is paid 1 year later, this will be in T1 (because we always start calculating the tax on 31 december, so in our case already in T0 ). Is my understanding correct?

2) Cost of capital
In the exercise lease versus capital sometimes we have the pre-tax cost of capital or the post-tax cost of capital and we must use the post-tax rate. What i have not understood is this. Can we get this kind of cost of capital problem also in the normal investment appraisal (so the exercise 4 of chapter 8 of your lecture where you said that the cost of capital is 10%, does this mean that 10% is the post-tax rate?)

3) Profitability index
I don’t understand why in the exercise 140 of BBP revision KIT they make PV/investment instead of NPV/investment. The result at the end don’t change but i am a bit confused

Thanks