Great OP mate.
I would disagree about Giroud though. I know he has come in from a lot of flack. Mostly from Arsenal fans themselves, and a number of other fans and even members of the press have mocked him this season, but I honestly don't think he is as bad as has been made out.
He hasn't scored goals at a rate of knots, and it should also be remembered that he has been brought in to replace van Persie who last season had a phenominal season, and has (sadly) continued it this season, so the comparrisons were inevitable. But he has been better than most would give him credit for, especially in his first season in an Arsenal side who has declined in recent seasons.
Giroud has 8 league goals to his name so far despite only starting 13 games, and coming off the bench 9 times. He has also managed 3 assists.
Walcott has been a revelation since playing in a central role recently. He has scored 10 goals despite only starting 12 Premier League matches and has come off the bench on 7 occasions. He has also provided 8 assists so far this season.
So we have to be careful, they are dangerous, and last week against West Ham, they absolutely destroyed them in a 10 minutes spell.
You also pointed towards the first half display against Chelsea a couple of weeks ago. You're right, they were absolutely dreadful in that first half. But they absolutely dominated the second half and were unfortunate not to come away with at least a point.
Defensively, they are frail at times. Mertesacker just doesn't seem to get to grips with the pace of English football, so in attack, we could well cause Arsenal some problems. Gibbs has genuine pace, so it will be interesting to see if Rodgers puts Sterling up against him.
The key is, as you said in midfield - Arteta (if available), Wilshere, Santi Cazorla and Diaby could cause us a number of problems if we allow them time and space on the ball. Midfield is the area we really need to win on Wednesday. If we come out on top in midfield, I think we can get something from the game, but if we sit back, like we did at Anfield and allow Diaby to steam through our midfield, we could be in trouble.