This part, I really did my homework after big time spent on try and error. Google PaaS doesn’t support Java, so sorry, out of the list.
The free tier of Heruko and Elastic Beanstalk. It works great if you app is relatively small, that is, 300MB for Heroku and 512MB for T1.micro for EB. If files larger than those two sizes, you simply won’t be able to submit. When I was blindly trying to fix my upload problem, there were no obvious statement about the two size anywhere ( as least where I looked.) In EB, the T1.micro will allocate at max 650MB RAM. If more, you will need upgrade for fee version.
MEAN infrastructure. They both have excellent support for these, in particular Heroku, users generally don’t need use npm install at all. They also have so many integrated libraries available thru their web. You could simply click on “add”. Also, Redis is available on Heroku as well. However, I didn’t figured out how to ssh to change anything on the server. In contrast, EB doesn’t have Redis at all, only PostgresDB and Dynamo for DB. The good thing is that it allows you to connect to the server via ssh. And so you could do more exotic things, hopefully. One trivial but definitely very time-consuming to figure out is that, you need zip your entire app with package.json and app.js in the root directory. If your zip will create a your subdirectory, you will never be able to see your app up (at least up until now). You will be able to see your app at /var/local/current. Again, don’t ever zip your dir, zip all files and subdir instead.
I didn’t explore the price tags in Heroku, but EB/AWS is not cheap at all, in particular, compared to Linode.com and digitalocean.com. I settled down on digitalocean.com, because it offers 2GB RAM + 40GB SSD for $20/month. Their tech support is more than excellent. Any questions so far were answered within a few hours, some within 30 minutes. The nice thing with digitalocean is that they provide MEAN as well. The catch is that something you will be your own, for example, DNS binding you need figure out yourself. They do provide excellent doc for help though.