You can create aliases in Google Apps without needing a new account. There are a couple of methods for this.
1) In the control panel, go to "Organisation and Users" then select the user you want to send the email to. Select "Add nickname" from the nicknames section. Add the alias ("sales" etc.) and it will point to that user and go into their inbox.
2) For aliases to multiple users, just create a group. You can use this to forward to accounts outside of your domain, and a group can consist of only one user, so this is actually a better method if you want to be able to view all of your aliases in one place.
Your auto-responders are trickier. Simple auto-responders can be done in Google Apps using the "Out of Office Autoreply" function (in Settings -> General on the individual account page). This will however require a dedicated account. You can do more complex things in this respect using the "Canned Responses" addon, which can be enabled from labs. This has support for sending a canned response in response to a filter.