My biggest issue is that I have not played on machines that are remote site and having to learn the current best practices. It has been about 13 years since I configured Apache.
Digital Ocean sounds like it is worth looking into.
http://html5dev-software.intel.com/ (this used to be called AppMobi / jqmobi, a reduced concept semi-clone of jquery mobile; Intel purchased it)
I've used all three. Sencha has a bit of a steep learning curve, but is nice. The Intel Framework is very easy to get started with; it's pretty fast for what it does; and so long as you're not trying to build the next Instagram, it'll work for a lot of different types of average apps. Using the Intel Framework, the scripting is similar to jquery, it fully supports javascript, and you can easily make ajax calls from the compiled app to a php / python / ruby back-end hosted somewhere else.
For a normal app, the systems side is pretty trivial. A modestly well configured $150 dedicated box will support 99% of all apps these days; and the bottom 50% of apps, based on usage, can be supported on a $20 Digital Ocean style account. If you're going to have a large active user base, then a very well run back-end is obviously that much more important. Today's powerful hardware provides a huge amount of slack on the back-end for a typical app, it's simply unlikely you're going to need to run at hyper efficiency.
I'll bookmark this thread, if you have questions I'd be happy to answer as many as I can here. It can seem like (is) a daunting challenge to build and launch an app.
One question I have in that regard is how to make an app that is most useable for the widest audience?