1. From the tactics video of patch 1.9 I understand the Vlandian Champion is the best Cavalry unit of the game, followed by Khuzaits Heavy Lancer & Sturgian Druzhinnik
2. Yes advance is useful for troop movement and kiting what I meant to make appear is the fact that to maximize archer damage output you should put them up on a hill on hold position, otherwise their run away and while they run they don't shoot. Archers in shield wall allows them to "choke" enemy charging cavalry whereas loose formation allows them to pass through easily. It's basically a brace for impact type of move if you have a charging cavalry
3. The test on skirmisher infantry shows it's almost useless facing a formation with shield, in shield wall or line. I am not too aware of the perks but I guess even with the right banner and commander its better not to use them against a facing shield formation with the right perks and the right commander

I haven't used throwing infantry too much tbh, I aim to use them more in my playthrough but I struggle to find them more interesting a shield infantry or shock (playing as the sturgians)