18 Year Old Caught in Possession of Alcohol in Virginia

My question involves criminal law for the state of: Virginia
I was at a party and someone said cops so we turned off the lights and laid low. One cop just walked in the back door, didn't knock and no one let him in. He then walked to the front door and let another officer in. They told all of us to stand up and started Breathalyzing us. The kids under 18 that had anything to drink were given tickets. The 18 yr olds that blew low were let go and ones that blew high were given possession of alcohol. The cops didn't do anything with the full bottles of alcohol around the house and just left. This was my second possession of alcohol charge. My first was when i was 17 and now i am 18. I lost my license for 6 months and 50 hours of community service the first time. I am just wondering:

a) Are the cops allowed to just walk in the back door if they didn't knock and no one let them in?
b) Can the judge see that i have a previous alcohol charge since it is a new record when i turn 18?
c) What should i expect from the court as far as losing my license and community service/fines?

1. Have your lawyer review the police report to find what they asserted as their probable cause for entry. We weren't there, and you haven't told us what led the police to the party.

2. You should expect that the prosecutor, judge and probation office will be aware of your record, particularly if your prior is in the same county.

3. I would assume you're charged with the Class 1 misdemeanor offense that, upon conviction, carries a fine of up to $2,500 and/or a year in jail and/or 50 hours of community service, and a driver's license suspension of up to a year.

When your license was suspended and you did community service, Was the case dropped?