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For tops, a 3-layer system is effective
Merino baselayer/ thermal type thing
polarfleece windbreak mid-layer for warmth and a top waterproof coat layer

Adjust according to temperature
Good...

A Howa 308 or a 2nd hand Parker Hale - 308 cos it is common and hence the ammo is cheap but a 270/7mm 08/ 6.5 all will do what you need easily
Don't start on deer with a 223 or smaller - later on...