Will I be fine after filling the application and is there any problem on the GC interview because I didn’t attend classes?

It should not affect it although you may be asked about it at the interview so be sure you have a valid answer prepared.

Generally, a person who entered the U.S. legally, later married a U.S. citizen, and now applies for adjustment of status on the basis of the spouse's immigrant petition, can adjust status even if he/she fell out of status after the entry into the U.S. However, in your case, there is likely to be a complication: you entered the U.S. on a F1 visa to get it, you represented to the U.S. Government that you would attend classes in the U.S. and then, you did not attend classes. USCIS is likely to view this as a visa fraud. If they do, you will be required to prove that it was not. Bottom line - get an immigration attorney before you file anything with USCIS.

F-1 visas are granted for duration of status [D/S] and unless a finding of your F-1 violation is already known to CIS, you should have no problem. Even if CIS knows of the violation, unless it is already a basis of a removal order or other adverse DHS action, your marriage to a US citizen, with a pending I-485 Adjustment application [green card] should suffice to forgive this infraction and the odds are extremely slim that CIS will deny your I-485 case for this alone. But I still strongly suggest that you speak to an immigration attorney because, apart from the F-1 violation, there may be other factors that may separately justify adverse CIS action. Without benefit of counsel, I am unsure you are aware of all the issues and of the attendant risks if CIS finds any other issue(s) justify a denial, marriage to a US citizen may not be enough to overcome a denial.

There could be an issue here if there is a finding of fraud. You should probably consult an experienced immigration attorney before filing anything.

Yes, you have a large problem. Hire a competent lawyer to help you.

It depends on the reason that you didn't attend school under the F-1, and if the USCIS officer is convinced by you that you did not enter the US under false pretenses.