Interesting (that you noticed these features only now).
The audio (plus popup) announcement of virus definition updates has been there for... well, 10 years at least, so certainly nothing new. Of course, you can turn it off (either the sound itself, or the whole update popup) in program settings.
Software Updater has also been around even in the previous version. Yes, many programs have their own updaters - but the fact is that many people simply don't update the critical stuff. Why it's relevant? Because that's the open door for malware into the system. So if avast! should protect the machine from malware, it asks you to update those programs. Again, you can set the particular programs to be ignored, or you can turn the software updater off completely.
As for the email notes - again a feature that's been there for more than 10 years, even though not enabled by default - you can disable it in the Mail Shield settings. Also, avast! should have asked you (when the first e-mail was being scanned) whether you want to keep those added notes - that's probably the popup you mentioned. It appears only once, to ask about this particular option.