Welcome! Looking forward to seeing your army progress. I’ve just been digging into some Russian Alt minis and definitely recommend them.
As for basing, baking soda is quick and simple, adhered with superglue. Scatter it with some rocks or sand grains for variety (or kitty litter so I’ve heard). Tabletopminions over on YouTube has a good video. Makes for great ashen wasteland.
EDIT: I used this on my Skaven