what exactly if the ruling on feats and battlefield conditions? I mean when you go to a game are you allowed to play battlefield conditions even if your opponent dosent want to? Im talking about a venu game not a home get together what is the official word on this, does this apply to feats as well? this question came up one player wanted to use battlefield conditions and the other didnt so what is the deal?

Basically...

1) Ask the judge how many rounds will be played. We'll call this number "X"

2) Construct a "hand" of BFCs. Your hand can have X minus 1 BFCs, so one round during the tournament you won't be playing a BFC.

3) That's it. Note nowhere do you see anything about someone else's permission

Also BFC's are unique so you can't play 2 Ordinary Day for example.
Your opponent can't prevent you from playing them if you bring them. If he didn't bring any then he won't be playing any. The same thing with the 3D and special object tokens. Your opponent cannot prevent you from using them and you don't have to share them if you don't want to. But you can let him use yours (that you are not using) if you are feeling nice.

The only time you can't play BFC's or feats or use special objects is if the scenario at the venue prevents it. Also remember to have your BFC's chosen before the teams are revealed. You can't look at your opponents team and then choose which BFC will help you the most. They are part of your build and if you don't have them chosen before the tournament starts then it's too late to add them.

But you can choose which BFC in your hand to use for each round. Once you have used one, you remove it from your hand and cannot choose it again for the rest of the tournament.

I hope that answers all your questions.

I like to use the "Non-BFC" proxy BFC for the rounds I can't play one.

That's partially true.

You do need to select your hand of x - 1 BFC before the start of the tourney. Once you've made your hand, that's it. No swapping out cards later in the tournament.

However, you do get to see your opponent's team before you reveal one of your x - 1 BFC. So, if you put Earthquake in your hand, and you see that your opponent has mostly non-flying characters on his team, you can choose to play the Earthquake.

From the Icons rule book (page 11):

STEP 2: PREPARE THE BATTLEFIELD
All players reveal their completed forces. Then each player rolls two six-sided dice and adds together the results. Reroll any ties. The player with the highest result is the first player. The first player chooses the map where the battle will occur. The two-sided battle map included in the Starter Set gives you two choices: an indoor map set at a chemical plant and an outdoor map set at a zoo. After the first player chooses the map, the player to his or her left chooses the edge of the map on which he or she will set up his or her force. If there are more than two players, continue clockwise around the table until everyone has chosen a different edge and identified a starting area—the area of squares within the purple line—along that edge. In two-player games, starting areas must always be on opposite edges of the map.

STEP 3: REVEAL BATTLEFIELD CONDITIONS
Players who have chosen to include a battlefield condition card in their forces reveal the cards simultaneously.