The idea is self-explanatory, it has been suggested and it was in Oblivion and Morrowind. Just that. If the horse dies, your items remain there with the horse till you transport them to other place.

The main functionality is that you can loot a dungeon and carry it to your current ¨base¨... we know we like to not leave those ¨not-so-great-but-magical-battleaxes¨ in the floor...

I need this, plus a way for companions to get a horse too. Also make horse flee and not fight.

yeah companions mounting horses would be good.

Saddlebags. Yes, I want this too.