I'm confused by your questions... which could be on me, or it could be because you misunderstand arena defense. So if you already know everything that follows, sorry. ;)
You can check the results of your arena defense team in the battle log screen, defense tab. There you see the people who attacked you recently and the outcome of these battles. You get no other notifications of people attacking you in arena, because anyway you don't get to actively play in arena defense, it's just the AI running the team that you have chosen as your defense team. The only way you could notice getting attacked, other than looking in the battle log, is that your arena rating decreases or increases without you attacking anyone. Your question above describes you attacking someone - so that's arena offense and has nothing to do with arena defense.
The reason that I advised to put the same team in arena defense as in arena offense, is that you need more or less the same things in terms of speed, tactics, synergies between your champions. The only differences are that 1) it will always be the AI running your team, so you may want to avoid some champions with particularly stupid AI, and 2) your opponent can see your team in advance and adjust his attacking team accordingly, just like you do yourself when attacking in arena. So teams which can easily be countered by a prepared opponent, are at a disadvantage in arena defense.
As LXZY said, you'll probably lose the large majority of your arena defense battles, but that's because you can't see the people who never even attacked you because they were afraid they would lose. So your arena defense may still be quite successful even if you see very few victories. In any case, losing on arena defense isn't a big deal. Yes, it decreases your rating, but as long as it doesn't get decreased too far too fast, that's not a big problem and you should still be able to climb to whichever tier you belong in based on the quality of your team. Actually, sometimes you'll see people who deliberately put an extremely weak defense team, like 1 low level champion, because they feel their rating is too high and they can't win enough battles anymore, so they want to drop back to a lower tier. Which is a win-win because at the same time it provides wins/medals by default for other players who encounter that defense team in their offense list.