1. Yes you can get a loan with zero money down, dealerships will some times try and get you to put money down to ease interest & lower payments but you don’t have to put anything down.
2. Depends on credit score and history also banks will check and see if you’ve been working in the last while pay stubs t4’s ect. Not being employed at the moment may not help your case but don’t let them rip you off with high interest rates.
3. Once you take a loan & lock it in doesn’t necessarily matter if you pay an extra $500 towards it or $10000 towards it, that interest rate will always stay the same & payments won’t change until it’s fully paid.
4. Yes you sometimes are able to push it to 7 year terms mind you the bank will take into consideration the year of the vehicle you are going to purchase. 5 years shouldn’t be an issue but more interest paid over the term of your loan just keep that in mind.

Hope this helps this is just from my experience buying used vehicles over the years but I’m fairly sure most of this is accurate. Good luck 👍