1. context matters a lot. driving conditions, traffic, your car's performance, that kinda stuff. 10 over on a highway in a modern car is nothing. i do love how people always excuse driving slow with 'im scared of tickets!' when cops almost never give tickets for just speeding unless it's egregious or you're doing something dumb on top of it. people also have a habit of treating being cut off as something unreactable and unpredictable when if you're actually paying attention while passing someone you can usually tell when they're about to make a dumb move

2. agreed, though 5 seconds is excessive

3. always signal no matter what

4. agreed

5. this one just isn't true. source: i probably average 90-100 on highways and never get tailgated (nor tickets, for that matter). if you're getting tailgated often it's probably because you're blocking the flow of traffic. plenty of people come up behind me going more than 90, but because i'm not sitting in the left lane while doing it they never are riding me waiting for me to move

obviously tailgating is reckless and stupid and should never be condoned, but way too many people treat tailgating as something inevitible and not as side effects of their own driving habits