1. OP says: Once you’ve cliffed, you have the right to buy shares in the company.
"Cliffing", when used as a verb, refers to firing someone just before the cliff-- not an employee achieving it. It's something you'd rather avoid.
2. If the company isn't publicly traded, you should ask to see the cap table. If you're employee #30 and your share is 0.05%, that might be fair if it's a biotech that has already taken a $100M infusion from the venture capitalists (who'll typically take 90%, in that case). For a web startup, it's terrible. You need to know how much equity the investors, executives, and employees at various levels have, so you can evaluate your likelihood of getting an improvement if you perform well. Without the cap table, you don't know enough about the startup to decide whether to take a job there.