First time i am going to work on (maintenance project) application that is already in production.The application was developed in ASP.net 3.5/C# 3.0(web forms) with jQuery,Ajax,Sql server 2005 and microsoft enterprise library 4.0.,WCF services.

Questions (bear with me if my question is wrong)

1) Is it possible to use Visual Studio (2008 with SP1) to debug the remote application (i.e already in production)?.What are the tools do i need to use in order to keep
track the things in case something went wrong?

2) Simply looking into Log file ,will solve the issues?

3) After having done with enhancements,is it possible to directly deploy the DLLs into production server.Won't it affect the running application?

Please guide me what are the procedures i need to follow.Client is ready to provide any tools for my support.(What are the area do i need to aware to handle production system)

Thanks in advance.