Having worked at a couple startups where my stock options didn't end up meaning much: the percentage of the company is kind of a funny thing. What I would ask them about more specifically is their plans for the employee stock pool. Stock options are (mostly) not liquid until there's been at least a couple rounds of funding, and each round of funding brings dilution to the existing shares.
Another bit of advice I wish I received before negotiating with start-ups: stock options are worth what they're worth now, not what they might be worth later. If you get 10,000 shares at a fair-market value of $0.01 that vests over 4 years, that compensation is worth $25 per year. (10,000 * 0.01 / 4). They will try to sell you on the shares sometimes being worth a lot more. I hope the shares are a lot more some day! But their expected value is their fair market value.
> what % of the company I'd be getting
A large percent of nothing is still nothing. Besides your own stock, ask questions to understand the financial maturity of the company. If it's a consumer product, how many customers have they signed up? If it's an enterprise product, have they signed any deals? If they haven't (which happens, signing enterprise deals can take 12-18 months) understand where the deals they are working on are in the pipeline. If they have 12 months of run-way but most of their deals are in the 18 month out horizon, understand that you are taking a lot of risk in joining that company. Also ask about potential customers that are not doing business with the company yet: why not? What are the blockers?
Don't be satisfied with answers like "our founders know this space, they've been here before." No start-up that has funding has an unimpressive founding team. There's no shortage of Ivy League/Stanford grads with years of experience at <whatever company impresses you these days>. Even with those pedigrees, 70% of those companies aren't going to be successful.
Another bit of advice I wish I received before negotiating with start-ups: stock options are worth what they're worth now, not what they might be worth later. If you get 10,000 shares at a fair-market value of $0.01 that vests over 4 years, that compensation is worth $25 per year. (10,000 * 0.01 / 4). They will try to sell you on the shares sometimes being worth a lot more. I hope the shares are a lot more some day! But their expected value is their fair market value.
> what % of the company I'd be getting
A large percent of nothing is still nothing. Besides your own stock, ask questions to understand the financial maturity of the company. If it's a consumer product, how many customers have they signed up? If it's an enterprise product, have they signed any deals? If they haven't (which happens, signing enterprise deals can take 12-18 months) understand where the deals they are working on are in the pipeline. If they have 12 months of run-way but most of their deals are in the 18 month out horizon, understand that you are taking a lot of risk in joining that company. Also ask about potential customers that are not doing business with the company yet: why not? What are the blockers?
Don't be satisfied with answers like "our founders know this space, they've been here before." No start-up that has funding has an unimpressive founding team. There's no shortage of Ivy League/Stanford grads with years of experience at <whatever company impresses you these days>. Even with those pedigrees, 70% of those companies aren't going to be successful.