Roasties questions

I cooking Christmas dinner for the first time and I’m practicing the bits I’m not so used to doing.

They were pretty good.

I used duck fat, but I’ve seen an increasing number of people using beef tallow. What do people use?

I put garlic, rosemary and thyme in with them whilst they were being roasted; but I saw some videos where they grind salt, rosemary and thyme together and use that to season the roasties at the end.

Anyone tried that? Is it worth the extra effort?

Finally what type of potato do people use?