To send an email via Google+, just post a "status update" of any length, then add the email address. Like any email, the message can contain photos, videos, links or location info. To send "attachments," you need to upload the file and link to it. This process has downsides (it's not as easy, and attachments aren't searchable) and upsides (it's potentially more secure, and you can change or delete the file after you've sent the message. It also gets past email spam and file-size filters.)
Here's the best part: To reply to your Google+ email, your recipient is moved over to Google+ to post a comment. You reply by posting a comment to their comment, and so on. These comments pop up in your real-time stream as they're posted. While email systems send the entire thread back and forth with each reply, Google+ strips this down to only one copy of the conversation history. The Google+ interface also inspires shorter replies.
To send an email to you, a stranger needs only to press a button on your profile page. Spammers can't copy, retain and sell your email address. If you don't want to receive emails from someone, you simply block them.
Emails, as well as replies, simply come into your Google+ stream along with everything else, or you can view a stream only of one-to-one communications by itself.
To break free from email, set up an auto-reply that links to your Google+ profile, and tell everyone who sends you email that they can reach you only via Google+. By forcing everyone to communicate with you via Google+ rather than email, you can end spam and other unwanted attributes of email.
Blogging
A blogging service is simply online software that makes it easy for you to post words, links, pictures and videos in reverse-chronological order. It enables visitors to see your posts and comment. This is exactly what Google+ does.
Google+ can be used for blogging. If you visit my Google+ profile, you'll see that my public posts really just add up to a blog.
I've been blogging on Tumblr lately (here's my "Tumblog"), because it's easy to post, it's easy to attribute links and sources, and it's social -- others can simply re-blog your post on their own blogs.
Google+ does all this. In fact, I would even rank Google+ as the second best blogging platform after Tumblr. The only thing it lacks is themes and customization, custom URLs and advertising. For the majority of bloggers who don't need these, Google+ is the best blogging platform out there -- better even than Tumblr.
Microblogging
If you want to, you can use Google+ exactly like Twitter. Post short "tweets," reference people with the @ symbol (which turns into a live link, just like on Twitter), link to pages on the Web, follow people, make yourself available for following -- everything.
The advantages of using Google+ over Twitter are that you're not limited to 140 characters, you can add pictures and videos directly in the post and you don't need the second site -- it all happens in your one feed.
Google+ makes Twitter obsolete.
RSS
Google+ doesn't support RSS (Really Simple Syndication), but it almost certainly will in the future (pretty much every Google service offers an RSS-feed view). In the future, you'll probably be able to subscribe to RSS feeds on Google+.
Also very likely: Those people, sites and blogs you currently follow with your RSS reader will probably have Google+ accounts very soon.
If you're like me, you use RSS to keep up with specific topics. Google+ has a feature called "Sparks," which lets you choose canned topic areas to follow (Movies, Comics, Robotics and others), or invent your own with a search. The results from these feeds come right into your Google+ feed.
Video conferencing
Google+ has the best videoconferencing solution out there, at least that I'm aware of. Google+'s "Hangouts" is free, and supports both group viewing of videos and up to 10 simultaneous users. It's also very smooth and reliable.