Legal Question in Business Law in California

It depends on the type of company. While most companies can pay a finder's fee, certain professions (including lawyers) are prohibited from paying referral fees (except to other lawyers in the case of lawyers). In the event that you are going to seek a finder's fee, I would recommend that you have an attorney draft the proposed finder's fee agreement.

You have no right to charge anything unless you have a finder's fee agreement in place before you refer them the work. What the terms of the agreement are is up to you and the company if you and they choose to negotiate one.

Finder's fees are generally legal, but they arise out of contract, not out of some kind of entitlement. If you had a finder's fee agreement in place before you acted as a finder, you'd be entitled to collect the contracted-for amount. However, if you had no agreement beforehand, you are essentially asking for a reward, and paying rewards depends entirely on the generosity of the benefitted party. There's no legal right.

You can charge anything the other party is willing to pay. Negotiate your deal and get it in writing in an enforceable contract beforehand.