How do Bottle Caps actually work?

Question

While breeding my Toxapex for HA + perfect IVs, I hatched my first ingame shiny Pokemon.
It has 5/6 perfect IVs but I'm still considering using it. The subpar IV is HP which for a mon like Toxapex is pretty crucial. I'd like to use a bottle cap to fix this but I have a few questions first-

1) Will having a subpar IV effect the EV training process at all?
2) Once the mon reaches level 100 and is hyper trained to correct the subpar IV, will the max HP increase?

I'm sure these are silly questions... but I'd like to know before putting in the effort to EV train this cutie.

Answer 1

1. No. Ivs have almost zero effect on evs. It is simply the higher the iv the higher the stat. Every four ev points only adds one point to the ev trained stat

2. Yes it will. Not just hp but any stat that is hyper trained will be set to its maximum value, which can then be further increased by evs and nature

Do note that hyper training essentially fakes the max iv. Meaning, the hyper trained Pokemon will still have its original ivs but when you look at its stats, the hyper trained one will have its value maxed out. This means that it's hidden power type will not be changed when you hyper train nor can the hyper trained stat be passed down to an offspring

Source:
Experience
https://pokemondb.net/mechanics/hidden
https://bulbapedia.bulbagarden.net/wiki/Hyper_Training