A few questions while getting back into the game

[Zuleran]

I'm recently coming back after quite a long break and i was talking with some people about possibly rerolling as i'm not really enjoying how squishy FA is without good gear. Someone was saying all i need to do is keep leveling as rank ups make mobs weaker somehow? Is this actually true? I watched my rank up and it didn't seem to give me any kind of stats or anything, but does it somehow just lower damage taken from mobs?

On a side note if i did happen to reroll what are some of the better solo classes? I don't really like having to play on other peoples schedule and would prefer if i can just do dungeons well solo. I'm not very interested in pvp. In nation war i've always been completely outgeared to the point that enemies hit my for almost double what i'm hitting them and i just have no interest in it other than just trying to get my honor rank up for accessories. Do any classes function better on budget gear as well? Are there any up to date leveling guides for where to farm when out of quests? I only remember this becoming an issue beyond 100.