Should I do everything on one character?

[Anova]

There are actually a lot of benefits when you diversify your skills. For example, Blood for Blood is a powerful damage buff obtained by cross-classing with Lancer. It is only obtainable if you level lancer to 34 however. You will find that access to these cross-class skills are beneficial. Even at low level, having access to the Protect buff and some healing can make solo-play and questing much easier.

You do gain a 50% xp bonus for completing leves and FATEs for any combat class lower than your highest level, and this does stack with the "rested" buff if you log off in a sanctuary or inn. This greatly speeds up your leveling by nearly doubling your xp gain. It is actually fairly easy to reach level 10 just by doing hunting logs and 2 or 3 FATEs. You will have new questlines starting from the cities as early as level 5. There are probably enough for 2 or 3 classes if you stretch them. After level 10, you can use guildhests and levequests instead of FATEs while finishing your hunting log. Once you reach lvl15, you can do dungeons and those should be much easier to find parties for after patch 2.1 in mid-December. Unfortunately, it does take a lot of grinding to level the alternate classes. It is just a matter if you prefer FATEs, dungeons, or quests/leves.