Best Practices for Complex Date Filters

Thank you for taking the time to respond to my post. I had contemplated creating a calendar table with actual dates and using it that way, but I ran across a couple of questions/challenges that I couldn't answer:

1. Will this approach work if I need to use two (or even three) different date relationships in the same CALCULATE? For example, in the complex measure I mentioned above, I need to filter based on three date columns (application_date, expiry_date, and cancellation_date)
2. How do I replicate the OR logic in some of the measures, like: 

contracts_table[expiry_date] >= period_start || ISBLANK([expiry_date])​

or,

contracts_table[contract_status] <> "CANCEL" || contracts_table[cancellation_date] > period_end

both of which are being done in the same measure too

Would really appreciate your input on these.

Thanks again.