Full disclaimer: I'm a noob to smartphones. I'm somewhat tech saavy. I will be getting a Nexus 4 this week. I've searched the forums and haven't had a clear answer.
How does one prevent excessive data use from push notifications, updates, etc? Is there a way to set Jellybean or any other Android OS so that when you are in an environment with wifi that the device chooses to use wifi vs data? Also, any suggestions from seasoned users on ways to limit data use when out and about and away from wifi?
If you're connected to a wifi network, you won't be using any data over the carrier's network.
For limiting data, there's plenty of ways. Most apps that poll for data will have a frequency (like a weather app will ask you how often it should update). Things like that. I also never do updates to apps unless I'm on wifi. But my advice is just to use the device normally for a week or two, then check your data usage and see what you're on pace for. If you're on pace to go over your allowance, then evaluate and make changes then.
Do you really need your mobile data on all the time? That is, do you have a need for constant notification about new emails or social media postings? If not, I suggest turning on mobile data only when you need it. There are a lot of toggle widgets available to let you do this with one touch--my favorite is , which is versatile and free.
If you do need your mobile data on all the time, you can set a data limit by going to Settings/Data Usage, checking "Set mobile data limit," and adjusting your data limit as you please--the phone will then alert you when you're approaching your limit, and stop all data transfer when you've reached it. If you check "Set mobile data limit," you can also tap the Menu button and then check "Restrict background data," which will limit automatic syncing of many, but not necessarily all apps. If you're going to do that, you might as well just toggle mobile data manually as mentioned above. Keep in mind that what I just described is based on my Razr Maxx's menu, so it might be a little different with your N4.
If you open Google Play and go to its Settings, there's an option to "Update over Wi-Fi only," which is for app updates. This will prevent you from wasting mobile data when downloading and installing new app updates. The Amazon Appstore also has a setting for "Use Wi-Fi When Downloading Apps," and allows you to select the threshold app size that requires wifi (from 1 MB to 50 MB).
A lot of games constantly try to access the web, usually for the ad banners. In general, turn your mobile data off when playing unless the game needs to access the web to check the license, or unless it's integral to playing.
I wouldn't worry too much about banner ads in apps as they don't use much data at all.
One trick I found very helpful is turning off the "Back up my data" option in System Settings > Privacy. It's not without a little risk because it saves wifi passwords, some app data, etc to Google, but it saves me over 200 MB/mo. I wish that had an option to backup only via wifi.
If you watch a lot of YouTube videos, go into the settings and make sure pre-loading is turned on. When active, plugged into your charger, and connected to wifi, it will download subscription and watch later playlists so you can watch them later without using your data. You will need net access so it can load comments, related videos, and such, but not the video itself.