Hello, both Nolvadex and Arimidex are used during the cycle but a more popular one is Arimidex.
Arimidex is reducing aromatization which is important because testosterone aromatizes into estrogen. By adding arimidex, you control estrogen issues that may appear during the cycle. Nolvadex is used during a cycle to control gynecomastia (but since arimidex reduces estrogen levels, it control gyno too). Difference is that Arimidex helps with all estrogenic issues. Nolvadex only with gyno. Therefore, Nolva is used in some specific cases when gyno is a problem (professionals know when they need Nolva instead of Arimidex).
For you, is better to go for Arimidex.
About PCT - I wouldn't go for Pregnyl but... Nolvadex.
You would start administering Nolva about 40 mg a day for 2 weeks after last Test E dosage. Then continue with Nolva for 2 more weeks at 20 mg a day.
As in terms of Arimidex dosage during the cycle - that's highly individual. you shouldn't use too much or too little. listen to your body as dosages may vary. A good starting point would be 0.5 mg Arimidex every 3 days. but you should increase or decrease based on how your body responds (read online about high and low estrogen symptoms).