What am I doing wrong

[Smallcaliberlargebore]

Just getting back into reloading after a couple year break due to kids being born and I want to check my methodology and confirm in not doing things too incorrectly so here it goes.
My reloading steps go in this order
-deprime
-sonic clean
-resize
- sonic clean
-trim
- chamfer
-swage primer pocket
-prime
-measure every load of powder on a beam scale
-measure a handful of bullets to find one of middle length set seating die off that and then seat all bullets checking depth occasionally

Main questions should I be trimming before sizing or after?
Do I need to measure bullet headspace if I don't how should I set my resize die every time?what is the most accurate way possible to measure powder charge?

And finally has anyone used the Frankford arsenal hand deprimer thinking of getting it

 

[TheOfficeT-Rex]

Trim after sizing. The sizing operation will push the brass up the neck, making it longer after sizing.

You should measure the headspace of fired rounds, and use that number to set up your sizing die. If you don't have a purpose made comparator, you can use a pistol shell as a stand in. Once you set the resizing die for that rifle, you really shouldn't have to touch it again unless you mess with the lock ring.

The most accurate way to measure powder is with a lab balance, but that doesn't mean it's worth the cost. Your beam scale can be accurate enough and tolerable for small batches. How nice a scale you need depends on your desired level of accuracy and the time factor. Fast, accurate digital lab balances are more expensive, and only get more so when you toss an autotrickler on them.

No experience with the frankford model. I have a Harvey deprimer, and it's solid. Does what it's intended to do. I have an extra pin, not sure if I thought I would need it but I doubt I would unless I accidentally deprimed a berdan case...