Start with the problem, not the solution.
Your problems are
stress among the employees, not just myself
some level of turnover and reduced morale
in recruitment [...] I cannot compete with what other companies in the area are offering
Has anyone in their exit interview actually mentioned free coffees at a competitor? Are you sure that more coffee is the right answer to workplace stress? Would people generally value a better benefits package, or do they really just want more money or better work/life balance? Are people leaving because they think the product is not going to sell? Because they are not listened to in meetings, or because they are given no indication of what they're working towards? Are people stressed because they're never told when they've done a good job or blamed for things beyond their control? Find out.
Are people turning down offers or not applying? What do they ask about? What do they find out about before you apply? Put similar ads from your company and a competitor side-by-side and see what stands out. How can you make a better impression?
As to the conversation, what's the CTO's take on the level of turnover and stress? Do they think it's a problem? Do they even know about the stress? Do they have a view on what the causes might be? What's their strategy at the moment? Tread carefully, they may not appreciate being forced to acknowledge their current strategy is "don't care"/"ignore the problem".
It might be that the ideas you have are worth having on their own merits but they might not solve the problem. That's fine too, and it's better to be honest about that.
In the following three cases, I would be looking at questions like 'does it work out cheaper to buy this for everyone or for everyone to buy this themselves', and 'if we buy this for everyone, will everyone want it'.
- The health benefits seem to be below what most startups strive to provide, being worse than what's offered by even the last two corporate jobs I've held (high monthly premiums, no HSA matching offered).
- There is no free drinks, snacks, or food offered, not even coffee (even that little retail shop in Arkansas could find room for free coffee in its budget).
- No offers of gym membership or alternative healthy lifestyle benefits.
All of these are potentially cheaper if you get them for the whole workplace require not only an amount of money, but also someone's time, both to set up and negotiate deals and then to manage day-to-day. Whether it's worth it right now may come down to (for instance) how long the queues are in the nearest coffee shop. You'd rather people wanting coffee don't have to go far and queue up, right?
Even then, remember that a small startup will not be able to compete on benefits anything like as much as a big company. If you want to attract good people from stable jobs into a startup ultimately you need to offer either good cash in hand or serious equity (combined with good realistic business plans, prospects and management) to offset the risks.
Also remember, once you start providing food you need to be willing to cater to different dietary requirements (and ask about these things in advance). It's not hard, but you could worsen morale if you act surprised or unwilling to change if not everyone can eat (or be in the same room as) the peanut snacks you brought everyone. Don't assume buying in bulk is going to work. For coffee, you'll also need space to refrigerate milk, more bins, possibly a better sink, etc., as well as the actual coffee-making devices and paraphernalia.
Insurance-type benefits are probably the best bet because if everyone needs insurance it's cheaper for businesses to pay for good insurance than individuals because there's less of an asymmetric information problem. You're doing that anyway, why not do that thing well?
This fourth one is a little different.
- There is no stipend for conferences, training, or education.
Do you mean there's no budget? Because that's not just a recruitment and retention issue, that's a really big business problem and as a team leader you need to bring this up at the next financial meeting or sooner if you have training needs. You need to be mapping out a prioitised list of skills you need and skills you don't have and start costing it out. If it comes down to something like "we have weak JS skills, we either need to pay for training or hire a JS expert" you'll have a strong case. Especially as it's hard to make good hiring decisions when you're assessing people on skills you don't have. Retention and morale effects of training are a useful bonus but less likely to be convincing.
In general I would avoid arguments that rely entirely on a need to improve morale or reduce stress. They may be objectively very strong arguments but those in a more senior position tend to be unsympathetic to abstract or 'third person' descriptions of stress and morale. They tend to perceive their jobs as innately higher-stress jobs (especially managers who like to 'delegate' stress), while at the same time tend to have a high tolerance for stress. If you need deal with stress, identify one or two specific causes of stress and have a detailed discussion just about those stressors.
Find the things that are preoccupying the minds of senior management, and if the problems you've identified aren't among them, explore that. Come with solutions to offer but don't push solutions for their own sake.