The Ethereum project originally laid out a timeline of milestones representative of different states of the ecosystem. In brief, they are:
Frontier, a "wild west" stage with emphasized user caution
Homestead, a more stable network which is no longer considered "beta"
Metropolis, representing a diverse ecosystem of user-friendly software including Mist the ...
The difficult bomb was actually added in a hard fork shortly after Ethereum's launch. It's not a necessary part of the protocol, and so if PoS isn't ready on time, it's most likely that another hard fork will delay or remove the bomb. In fact, if a portion of the Ethereum community desires to still use PoW, or does not agree with the final PoS protocol, ...
Notes on the above-mentioned attributes:
increase value of ether: this would be just speculation
improve network somehow: experimental network (frontier) will effectively have been under observation long enough to be declared "stable" and no longer "potentially unsafe"
changes: see homestead release documentation
The whole purpose of DApps is that you don't need to setup a back-end for them, since the Blockchain acts as a common back-end shared across all DApps. Most of the time, a simple static HTML/JS/CSS front-end application will be sufficient for DApp projects. For my DApp projects, I make heavy use of AWS S3 to store the front-end single page applications from ...
Past releases can be found here: https://github.com/ethereum/solidity/releases
Future roadmap, as far as there is one, can be found here: https://github.com/ethereum/solidity/projects
It might be also worth looking at the open issues, perhaps focusing your attention on those marked with the feature tag.