How to: Release a commercial program?

Hey guys, what's up? I am a C# developer and work in a energy management company and I am starting to do something by myself as well... So, in the work I don't have that much time to see this kind of stuff and I come here to ask you guys this:
What do I have to do to guarantee the most professional software release? What kind of tools for versioning I've got to have?
If I release a software and It has some bugs, how can I fix it without making the customer install the application all over again?

Thanks!