DDAL-01 through DDAL-04 all say they are for adventurers level 1-4. Does character level correspond to the event? For example, are all characters in "DDAL 10-03 Divining Evil" level 3?
No, the level 1-4 is for any character in that level range, from the walk-on with a pregen character to the person who has played 8-9 times and is on the cusp of hitting level 5. The 10-03 is the "episode number", i.e. season 10, adventure 3
Similarly, do all events have to be played in order, or can you jump into DDAL-02? And if so, do you play with a level 1 or level 2 character?
There is an overarching story that you might get confused on if you play out of order, but there is no requirement to do so. And you can play with any character that fits the level range (Once I ended up playing most of a series, but missed the first few adventures. I eventually came back and played them later, but by then my character was 2 levels higher, so he was stronger at the start of the "campaign" than at the end :P)
If I'm only able to do one event, is this even the place for me? Or should I be looking for a one-off event elsewhere? I'm a D&D veteran who'd love to give AL a try, but I don't want to mess up anyone's multi-event, multi-day epic
One event with a DDAL is a great way to start. As long as you are familiar with D&D 5e, you'd be fine at any multi-event epic. All DDAL does is limit build options for streamlining/balancing and standardize loot so you don't get a GM who gives everyone 5 magic items at level one. Otherwise, its still D&D 5e.
I should clarify here, a multi-event epic is a specific event, a la Gen Con | Gen Con Indy 2021, the D&D eXperience. That one is very specific, and you would need to commit to going to all of them in order.
The season 10 adventure path has multiple events, and they are connected (and probably epic), but there is no requirement or expectation that you play them all or in a particular order. These are the "episodes", a la "DDAL 10-03 Divining Evil"
~Komori