My buddy has season tickets in 408 and I've sat there twice as his guest. Once for a Titans game and the other time for a Texans game. You should know that these seats are still 2nd level seats even though every section in the upper level is denoted as '400s'. The 200s are all on the first tier so what it comes down to is fans have a great view everywhere in the stadium.
408 will put you right on the 20 yard line towards the south end zone but doesn't feel any different than the 50 yard line seats. You should probably avoid all of the double lettered rows in section 408 since those are at the very top of the stadium but those are always where you'll find the cheapest tickets.
Ownership covers up with corners of the upper deck to help shrink the capacity of the stadium. Back in the day, the Jaguars would fill those seats but they haven't been competitive in a very long time.

Everbank Field is fairly easy to get to via the major freeways in Jackonville, and parking is usually not an issue on gameday, just expect to pay $25+ for a parking spot. Local neighbors and churches charge fans to park on lawns and streets. The parking lots at the stadium usually fill up quickly with tailgaters and all of the lettered Lots are usually sold out in advance. Make sure you bring cash, or you can go on ParkWhiz.com and purchase your parking ahead of time.