Actually the leveling has been speed up for lower levels, not sure if you check the "postmaster" there may be an item there to get you boosted in level. Do check.

As for leveling, its pretty direct...and a no brainer..just lvl. once you hit 40 your leveling would stop but there's a thing called light level which is the number by the top right. This lvl derive from the lvl of the items that you wear later in game.

as for skills...those u can play around as they can be change anytime..so no need to worry.

Do more bounties and u will rank up quickly, also complete the story. By the time u finish all stories, u shd be close to lvl 40.
Once u hit 40 u can do strikes and other end game content to rank up further. Pls refer my previous post on the recommended lvl for end game content.

Of coz, pls add some of us so that they can carry u throughout ur leveling period. For subclass, if u wish to play sunsinger, u can focus to rank it up once u unlock it in lvl 15. I suggest u try out every class coz u need to rank up all of them eventually.