custom entity questions

hey gang, recently i have found myself getting into Minecraft modding however while testing my entity a few problems and questions came up such as:

1. my entity (when spawned) instantly de-spawns with me only getting a slight glimpse of it by rapidly spawning via spawn egg, how do make it not? (FIXED)

2. is there a way to get the entity to cling onto ceilings and walls kinda like a shulker?

3. can i have a slab change its texture depending on how much health the entity has and if it is currently angry at a mob?

4. can i have a slab spawn my custom entity once on top of it or below it if its upside down?

5. how do i get the entity to open a gui when i right-click them? (FIXED)

6. is it possible to have the entity act hostile towards the player but at the same time be tamed by the same player?

7. how do i set what the entity is tamed with?

8. can someone hand me the spider and enderman glow texture?

9. can i have my entity spawn within a specific part of a structure, example: the ceiling of a pillager tower?

10. can i have it so the entity changes what it attacks when tamed?

11. (NEW) my entity isn't facing the enemy while attacking them, how do i fix tbis?

if anyone is wondering im making the entity an automated turret thats why i thought it'd be nice if the placement was akin to shulkers, so if you have any advice on making said automated turret that would be nice, also i haven't gotten to test the shooting of the thing so if you know if any problems would appear during shooting let me know.