I just got the game and I am trying to figure out the rules. I have watched the Watch it Played video for this and I now have read most of the learn to play rules (not the hobby section yet).

In the Command Phase why would the player that has priority issue orders first? I would think that it would be more beneficial for the person that has priority to place their orders after the person that did not have priority. That way they could react to what the other player is doing that did not have priority. The person with priority is generally giving orders to less units.

Is this just something to keep the balance of the game since the person with priority is going to move and attack first with their unit? Any thoughts or opinions from people that have a few games in would be great.

Is there any synergy charts in the forums or anything with things that work well together? For instance, a unit with charge being able to take an aim action first, then do a charge and have a free attack after from the charge for the re-rolls? Is this possible right now using an aim action? Luke is the only unit I see with charge in the base game, but there may be better things for him to do in a turn.

Are there any condensed topics in the forum like that in general to help a new player with tips like that in game?

In regards to issuing orders, I think the player with priorities issues orders first for game balance reasons, like you suggested. Going first can be a significant advantage, as it gives you an opportunity to suppress, severely damage, or even completely defeat an enemy unit. Allowing the player with lower priority to react while issuing orders offers that player some small measure of counterplay.

For example, Player 1 plays Ambush and Player 2 plays My Ally is the Force. Player 1 issues their one order to a unit of speeder bikes that is threatening one of Player 2's Rebel Trooper units. With some luck, the speeder bikes can cripple that unit before they have a chance to activate. However, in this hypothetical scenario, Player 2 can now use My Ally is the Force to give that Rebel Trooper unit a dodge token. This dodge token might not save them, but it at least gives Player 2 a chance to mitigate some damage. Even though the speeder bikes might still kill a couple of troopers, Player 2 was still able to influence the outcome, and that (generally) makes for more satisfying gameplay.

Edit: Btw I have a blog here with my take on different unit's strengths and weaknesses. It might not be exactly what you're looking for, but I am slowly adding more content and plan to eventually have articles on specific tactics...