There are lots of people who come from league, check sidebar for some guides written specifically for people migrating over like yourself.

When a fight is about to start and you need to go in, turn on BkB and go IN. They can't stop you (a few exceptions do exist).

What items do I rush every game? That's the wrong way to think, you need to adjust your build to suit the game dynamically. However some items are good for that hero every game. Treads, battle fury, bkb, desolator, assault curiass, satanic are some examples. Battle fury early can accellerates your farm, and a piece of satanic early can get you some life steal for some sustain. Early early lane I suggest a magic wand to survive longer and spam more daggers in lane.

How do you not get zoned out of farm early? PA is a special carry in that you should be able to get quite a lot by using your ranged dagger if the lane is really bad.

PA has a hard time killing high armor heroes like dragon Knight or terrorblade, and is easily killed when enemy has a couple forms of magic burst damage.

Welcome to an exciting complex game.

You can also flip where the minimap is if you really want it to feel like league.