1: Full support to this! Zulrah isn't an endgame boss and currently you need to have max mage to be able to do significant damage to it which may be one of the reasons many people avoid it.
2: Once again, fully support this! I'd like to see an increase to seed/herb drops across the board and one recommendation wouldn't be to remove Ranarr Seeds, but just add in the other essentials (Toadflax and Snapdragon mainly) so we get a variation and it doesn't become overpowered for irons.
3: Definitely support. It's not a major issue, just a bit of a nuisance.
4. YES PLEASE. Superiors are fantastic on OSRS because the tasks offered are generally much higher (the ability to get 100-200 of an NPC for a task) in comparison to our max default being in the 50 range. Superiors could definitely be increased, or the Slayer system could be reworked to larger tasks.