I promote Google Apps solutions for all of my clients. I also at the same time tell them to stop using Outlook completely. I used to be an Outlook junkie like many of my clients and I understand the difficulty of eliminating the use of Outlook and going to web based Google Apps email only.
Yes, it is possible to still use Outlook along with Google Apps enterprise, but eliminating outlook all together is a better solution IMO.
When you stop using outlook you will loose some functionality but there are work arounds that you will find to be better solutions.
Sorting by Date/Subject/Person
Many clients like to search for stuff by sorting outlook by date/subject/person. I myself used to think this was great but the search function of Google Apps works so well that loosing this ability will be forgotten as it is unnecessary.
Google Apps does folders, just that they are called labels instead. You can also have nested labels (folders). You can even import all your data from Outlook to Google Apps and the import tool will convert all your folders to labels
You don’t loose this ability. In fact the web based solution of calendars works better than Outlook does
This ability really isnt native to Outlook but is part of an Outlook + MS Exchange Server deployment. There is no solution with Google Apps but there are 3rd party services that fix the problem but I have not tried any of them.
Is Google Apps the best solution for email/contacts/calendar for small businesses?
Yes, for the price and the features there is nothing better.