This is indeed an interesting thread.Kudos fellas,very informative.I hope all the technical answers at least are kept updated in the first post (might as well as one of the mods to reserve couple of posts for the thread).
Am I allowed to ask questions ? If anyone want's to,give the below question a try.If the answers is convincing,I'll leave some merits.

My question :
How to calculate transaction fees before sending bitcoins ? A one liner answer may be , just use electrum wallet and you should be fine as it has both rbf and cpfp option . In case you need more info, use this website : bitcoinfees.earn.com . With electrum, you can preview size and tx fee too .