"I'm looking for a stock position of about 2% once they mature, and $xyz,000 salary, and medical."
How else could you say it?
I am struggling to word this in a way which does not sound crass
Honestly set the "crass" idea aside.
When you go in to McDonalds to buy a burger, the person says "That will be 98 cents, thanks." It's the same. Just state your price.
If you don't simply state what you want, it will be very confusing.
I estimate that the value that I can provide is worth at least X salary and an option to take a stake in the company. Given my current financial outlook I am more motivated by the prospect of owning a piece of the company's success than I am by the immediate gratification of a paycheck. I hope that this information helps in the formulation of an offer.
I would utterly set aside this language.
You don't have to explain "why" you want a salary, "why" you want shares of some form, or "why" you want medical.
(For that matter, the company doesn't have to explain "why" they want you to write software, while, you are there each day!!!)
It's super-ultra confusing if you start explaining "why" you want shares, salary or medical.
Please understand that, regarding the founders, every single conversation they have all day is about nothing other than people (on the investor side or the employee side) stating percentages.
Do be aware that when you talk about positions, the "actual numbers" can be confusing and meaningless. For example, if you get "three thousand" or something, that could ultimately be (even if everything works out) 0.01% of the whole company, or, it could be 10.00% of the whole company. To make a simple example if X says to you "we're going to give you 5,000 shares of this company!" there's a huge difference if the company overall has 50,000 shares or 2 million shares. And unfortunately there is a vast variety of ways you can be given share-like instruments, and the details can hugely change things.
You should google and read endless articles, https://getoutlaw.com/blog/equity-primer-for-startup-employees/ , https://www.startups.com/library/expert-advice/startup-equity-101 , https://www.secfi.com/blog/stock-options-101 etc.
Don't forget too that they may toss around valuations of the company. So they might say something like "We're gonna give you 1%. The company is valued at $2million, so that's 20 grand!" "Valuation" is completely meaningless until someone has actually paid money for some part of the company.
And finally don't forget that if you are given one of the many possible instruments, there can be (serious) tax consequences, whether immediately or later.