I created a Bitcoin mining calculator in a form of a google spreadsheet to simulate various long-term (5 year period) mining outcomes:

https://docs.google.com/spreadsheets/d/1wAvS5Pb0jdjvTiypFSDojLF5n8ep12GrWDZPPuysjog/edit?usp=sharing

Specific questions:

1) Beside the network difficulty (i), the mining hash rate (ii), and the block time (iii), the certain exchange rates (iv), and the power consumption indicators (v) is there any other parameter that could increase the precision of a real-time mining calculator?

2) Are there any 'hidden' correlations between the number of transactions in a block, or the transactions fees and the actual mining capacity?

3) Despite the 'spreads' between block validations, in the long term the protocol adjusts to the average 600 s block time, so I suppose that it is unnecessary - even wrong - to use a block time variable other than 10 mins. Is that correct?

Directives / insights

I would like to illustrate a plausible 5 years long mining scenario. I intend to make calculations for each day from today until the end of the 5 year period under investigation.

I know that it is almost impossible to solve the following problems, but I need some advices about the followings:

A) I wish to simulate changes in the network difficulty. I think it wouldn't be wise to use a constantly increasing value. Do you have any suggestions about the actual test values and methods to calculate a realistic network difficulty scenario?

B) I would like to designate theoretical dates of block reward halving in the following 5 years that are not unrealistic. What do you think? How many halvings are expected in the next 5 years, and approximately when?

C) Finally, the most uncertain variable: the exchange rate of Bitcoin. Do you think that it is a good idea to mark a certain average value (e.g. $8.000) and use it as a constant reference for the entire 5 years period?

Thank you very much for your help!