That's right, SSRS "Business Intelligence Development Studio" (or BIDS) project files won't work with the Visual Studio 2010 shell. But there is no reason you cannot simply use the Visual Studio 2008 shell, which is what the SQL Server client tools should be installing for you. Just be sure you install the SQL Server Client Tools into the DEV environment, and you should have everything you need to develop the reports. Where it gets a bit clunky, is if you want to package them up and deliver a Feature for deployment, but you don't have to deploy that way. You could simply upload to a SharePoint Report Library manually. Just depends on your change management process.
To address your follow up questions (posted as comments):
The SQL Server Client Tools are part of the SQL Server installation media. One of the very first options in the wizard is to choose which components (SSAS, SSRS, Database Engine, Client Tools, etc) to install. Assuming you already have the DB Engine and SSRS installed, you will need to rerun installer and select the Client Tools only. Though written for SQL 2008 (not R2), this posting may be helpful: http://www.mssqltips.com/sqlservertip/1807/sql-server-2008-client-tools-installation/. At least to get the basic jist anyway.
I am pretty sure that SSRS will integrate with SharePoint Foundation, so you should be fine with SharePoint Server 2010 Standard. You may not get a few of the OOB BI features (like a site template dedicated to SharePoint), but I believe the SSRS Add In (which is free) will install all of necessary Central Admin, Content Types, List Templates, etc needed). This article seems to back this up: http://technet.microsoft.com/en-us/magazine/ff686706.aspx
If you have an existing SharePoint installation, you can download and
install the add-in at any time. The add-in installation process adds
the necessary pages to the SharePoint Central Administration as well
as the new Report Server content types for existing SharePoint
Libraries in sites using the Business Intelligence (BI) Center site
On the SharePoint side, you can configure integration on either
SharePoint Server 2010 or SharePoint Foundation 2010. Both support the
installation of the Reporting Services Add-in. If you install
SharePoint and Reporting Services on different machines, you must
install the same version of SharePoint on the Report Server. For
example, you would not be able to install SharePoint Foundation 2010
on the Report Server if you were using SharePoint Server 2010 as your
Web Front End.
Also, once you get to the point where you have all to tools needed to start building reports, you'll probably want to refer to this MSDN article for actually building reports against a SharePoint List: http://msdn.microsoft.com/en-us/library/ee633650.aspx