They have a chain, you won't find too many (if any) cam-in-block motors with a belt. For the daytona, you don't have the MDS, so you don't have to use the 5W-20, but it's recommended. I know people who use 0W-20, with no issues. If you're asking the TYPE of oil, then join the debate.
How would you like to upgrade the lights? New assemblies, bulbs, HIDs? There are lots of options.
As for other mods, the list is long, and only based on your pocketbook and common sense. If you're like me, one's bigger than the other
The daytona already has 4.10 gears and a borla exhaust, so no need to upgrade those