fluid lines and external filter questions.

[meir]

Hello guys.
as i'm finishing the installation of my rebuild transmission (700r4), i'm working on replacing the hard lines with flex an-6 lines.
for the transmission side, i use these fittings:

https://www.amazon.com/gp/product/B003CGV03U/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

as you can see from the pic and info, the transmission side is 1/4" NPSM, and the fitting comes with copper washers. so hopefully no leaks here.
the radiator side on the other hand, is 1/2-20 thread.

https://www.amazon.com/gp/product/B000CPIJS8/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

so first question, do i need to use a sealer on the thread?
i have this in hand:
https://www.amazon.com/Permatex-592...&sr=1-1&keywords=permatex+thread+sealer+59235

also have the prep activator.

for the second question.
i also intend to install an external filter on the return line, and wonder if anyone who done it before can recommend location for the filter housing.
this is what i have:

https://www.amazon.com/gp/product/B004XONNOO/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

thanks in advance.

Meir.

Edit: truck is 89 K1500.