That depends on what the contract says, and what the contract says might differ from one situation to the other. If I don’t trust a client to pay, I’ll insist on payment in full upon delivery. In a normal situation, I just request payment within 30 days. If it’s a logo, I’ll specify in the contract that the copyright transfers only upon payment in full, which might be in 30 days or sooner, depending on the contract. Keep in mind that the contract needs to be agreed upon by both parties and, often, needs to be modified to meet the client’s concerns.
Generally, yes, but the final word is in the licensing agreement you obtained from the stock agency. That agreement differs from stock agency to stock agency and, sometimes, between how the artwork is used and the artwork in question.
It depends, but yeah, it can be problematic. With an in-person thing, it’s easy. Sometimes clients have their own document signing service. Sometimes it’s a PDF. Sometimes they sign, send it to me, I sign and send it back. Sometimes, it’s nothing more than an acknowledgement in a string of emails.
Most jobs for most freelancers don’t deal in the tens of thousands of dollars, so it’s not as though things need to be as bulletproof as negotiating the sale of a skyscraper or fleet of aircraft. In most freelance instances, where there is an issue, it’s typically a small claims court thing, and the judge isn’t going to wade through 12 pages of contracts. The judge will, more often than not, pay as much attention to an email agreeing to something or other as a full-blown signed contract. It’s not like there are teams of attorneys raising objections, filing briefs and calling multiple witnesses.
For what it’s worth, in all my 30-plus years of freelancing and being careful, I’ve only had to take two people to court and that was in my first two years. Since then, I’ve learned to spot the problems and stay away from them. Pursuing legal remedies is something to do only as a last resort because, in general, the courts don’t really help all that much when dealing with professional deadbeats who have learned the system and know how to get around it.
The most important thing to do is do everything possible to minimize risks and be careful. This means, turning down iffy-sounding work, making sure you get paid first if you’re uneasy and, most important, upholding your end of the contract because as inconvenient and awful as it is to sue someone else, it’s even worse to get sued yourself.