side quest questions

1. Can I go back and complete all side quests even if I'm further along in the main quest? Or do some side quests become unavailable after a certain time?

2. Is there a quick way to tell when side quests become available in a particular town/region? Or do I have to cover the entire area looking for people with exclamation marks? Maybe it's already been suggested, but NPCs with side quests should have some distinction such as a different color/shape on the map, or the word 'quest' after their name, so I can quickly go straight to them when I enter the area.

1. Side quests do not expire: you can do them whenever you like. There is one exception though; the starter areas in Prophecies (called pre-searing). This is because a certain event in the game moves forward two years. Missing side quests is no big deal though.

2. Not really. There are probably quest checklists on one the wikis if you're interested in completing them all. Without them though you'll just have to check back at the main/quest giving NPC's every now and then.

There's one side quest in NF though that will be gone if you don't do it before completing one of the missions.

There's also some quests which depend on your choice, they open up branches of quests which are mutually exclusive. But usually you can get back and do the other branch after you finish the campaign, so technically you're not missing anything.