A few questions about making & improving a Homunculus

[eyebreaker7]

1: Would a homunculus with more HD be bigger and therefore require more of your blood for the mixture?
"A homunculus is shaped from a mixture of clay, ashes, mandrake root, spring water, and one pint of the creator’s own blood."
"A homunculus with more than 2 Hit Dice can be created, but each additional Hit Die adds +2,000 gp to the cost to create."

2: How do you determine size increase corresponding to HD increase? Is there a chart or something?

3: I see that there's an "Improved Homunculus" feat that goes into detail in the "Magic of Eberron". Is there by chance a write up of this online somewhere? I did a google and found some that say they're home brew and I don't have "Magic of Eberron".

4: My guess is the creature in NwN 2 is a homunculus created by the Red Wizard that finds you in the beginning of that part of the game??? I'd like to make something similar. Would it be considered home brew and I just make it up however I want (with DM approval of course) or are there templates I could use?

[Quentinas]

The homunculus from d20srd have a maximum of 6 hit dice size tiny , so probably not more blood to be created but more money because there are more hit dice
To see the feat i suggest the site dndtools, and try to search improved homunculus or magic of eberron. and for the last question sorry but i didn't play NwN 2 so i can't help

[eyebreaker7]

Thank you! That site should help a lot.

[ShurikVch]

Secrets of the Alubelok Coast book (Kingdoms of Kalamar) have Sobetetan Messenger homunculus.
It's mostly like "normal" Homunculus (https://www.d20srd.org/srd/monsters/homunculus.htm), but with a handful of minor changes (starts at 4 HD, have swim speed 50', etc).
One interesting thing about it: you may improve its abilities by changing components which you using during its creation (which would cost some gp, obviously). For example: addition of kraken tentacle will give it +4 natural AC; powdered sea cat teeth mixed with sea cat scales - increase bite damage to 1d6; aboleth scales would double the empathic link range; etc...