Grind recommended zones, only quest-line should be reina strait just because it takes around the same time as grinding and it changes up scenery.

Just loot equips that fit your class when training. You can honestly bare thru most levels without needing to physically buy equips until 100+. Even then though, you'd be looting equips from monsters you are training at.

You can use maple guide to help you figure out places within your level range, or mainly focus on "Maple World" right click the map to zoom out, click on certain regions to zoom in. You can also double click on one of the circles that you wish to travel to and an arrow will help navigate.

A pet can do several things such as auto health pot, auto mana pot, loot, auto-buff, auto all cure etc. However, these skills must be bought in addition to the pet. Looting of mesos/items should be included with any pet purchase and certain pet packages will include skills already, you'll just need to apply them to the pet. In my opinion, pets are very worth buying.