Answer 1.

Advance payment would cover all proposals that are for those endeavours which are not yet a fully functioning viable functioning working/tangible product or service.
Literally a payment for something that is only in the planning phase or pre-completion phase.

Answer 2.

There is no reason why a proposal couldn't be made for multiple categories. It is left to the discretion of the party submitting the proposal.

Open ended discussion:

"KPI"

Fully understand where you are coming from. As I transparently stated, GP brought that to my attention and it was the first time that I myself came into contact with that acronym too.
However, because it was brought up, it lead me to check it out via our good friend Google and in less than a few minutes it was clear what he meant.

The fact that the term already exists and has a very clear purpose (definition) makes it somewhat easier for those submitting a proposal to list what their "units of measurement" are.
Again, it is left to the discretion of the party submitting the proposal.

There is no reason for us to reinvent the wheel, as this is a highly competitive business environment which we are in and so too are the proposals competing with each other for the votes/approvals of our stake holders (aka community).

Each and every party submitting a proposal has the freedom and liberty to express themselves however they feel is best and by using defined terms that have very clear purposes it actually makes everything all the more clearer/transparent.
If we start reinventing the wheel, then we shall definitely have a bumpy road ahead of us.

i.e. it took me literally seconds to get the following:

Again, we are in a very competitive business here and although we do not necessarily expect every individual to be "business orientated" or familiar with all the terms used in business, that should be no reason for us to avoid good business practices in utilizing well defined terms that already exist.
Especially those, such as this one, which are simple to comprehend and make everything about the proposals being submitted all the more transparent.

We can't expect transparency if we do not insist upon it.
If we insist upon it, then we need to clearly/definitively insist upon the means.

"Key Performance Indicators - KPI" are defined, understood and by all means make every voters/stake holders life much easier when assessing proposals.

Why would anyone vote on something for which it is unclear/non definitive as to 'How the voter can clearly see what is being achieved and how it is being achieved.'

idk, it is up to those voting to decide what they wish to implement.
I think that I have made some constructive suggestions in the initial reply and elaborated on them (tried to further justify them) here in this comment.

Whatever the case may be, I am satisfied that anyone reading this shall think about it and understand that we are looking for means of ensuring all proposals are transparently auditable by those who need to vote on them.

I sincerely hope that this post and all its comments will be read throughout the entire life of Hive as this type of approach as this post here is what shall set us apart from 'the others':
Transparent, open and public policy making procedures.

Cheers.