Bike build - Opinions/Suggestions needed

For the price of that frame you can buy a good quality second hand bike on here that will meet/surpass your needs.

Also why not try ride fixed from the get go? Why only freewheel for commuting/long rides?

I could but I've gone through so many second hand bikes - so this time my plan is to fix myself up a fresh bike and in the process learn how all these parts fit/work together to be a little more self-reliant in the future.

I prefer freewheel riding on dangerous routes into work but yeah, I'd likely ride fixed on +10mile rides anyway. A little backwards I admit, but just preference I guess.