The .NET Framework 4.0 is completely different from 4.5. It's very possible to have one and not the other and it diffenetly doesn't hurt to have both. I'd suggest that you make sure you have 4.0 installed and try reinstalling it if need be.

Does Idle Master say it's trying to idle a game? What OS are you on? UAC enabled? Tried signing out and signing back into Steam through Idle Master? Tried deleting the IdleMaster folder from C:\Users\YourUserName\AppData\Local\ and restarting IdleMaster?

Looks like you have User Account Control enabled. You could uncheck the checkbox and it "should" stop asking you each time or you can just turn off UAC by going to Start, Control Panel, User Accounts, Change User Account Control settings and slide the slider all the way down, click OK and restart your computer so the changes can take effect and you should be good.

I don't know what window you're referring to. Do you have a screen shot of such window? Mine just moves onto the next game automatically.

Does steam show that you're in game? If so then do what Shadok say and be patient.

1) The number of card drops remaining is the actual number of cards remaining based off of the profile that you're signed into. (I still have 725 card drops remaining myself).
2) The timer is there for when the application will check to see how many card cards is remaining for the game (or games) that it's idling and how many drops total remains. It has nothing to do if and when you'll get the actual card since that's completely random for each game.
3) All there is left is the portal version which can be found at http://www.steamidlemaster.com/idle_master.zip (not sure if you've downloaded idle master before or after the March 2nd announcement or not)