you can play the entire game (with the exception of bitterblack island) without grinding. Just remember to always check request boards (1 in cassardis, 1 in the training camp, 3 in gran soren) and accept all quests, since there's no limit and they stay active. All "kill X enemies" will be fulfilled during normal play and bring XP. It's true there's no indication of level requirements, but you can get comfortable by doing story based missions inside gran soren first
About travelling, you'll need to go to the black cat shop (google it) and buy ferrystones. they grant instant travel to cassardis and gran soren, and any portcrystal (an item you'll get during some quests) you placed on the world map. It's a good idea to place them at intersection and places far away from the towns, since you'll need or want to visit them multiple times to complete quests.
spells only heal up to the current limit, but potions heal regardless of the limit and can reach the maximum health. So stock on potions.
you can give commands to pawns with the controller cross.
Guides are only necessary to get certain items, otherwise it's not a very difficult game.
hope this helps
weapon skills are specific to vocations, meaning if you learn a dagger skill as a strider, you wan't know it as an assassin. however, augments are not specific, so you can play as a fighter to learn defensive augments and continue as a mage with these augments active. Swithing vocations is actually advised.
fresh from the beta:
-pathing issues: sadly not fixed, and worse than ever. A sword swing might be enough to make an enemy fall from a cliff, then send you to your death as well
-improving the graphics: yes and no. the graphics are a bit more defined and detailed, but it's mostly the framerate that makes a complete difference. No more lag, smooth combat, even with a lot of enemies.
-combos: nope. just one combo per weapon, performed by mashing buttons.