- It can be like this on windows with an under-powered computer. I have a netbook, and this happens sometimes.
- Everything else you've described is mostly nothing to do with silverstripe itself (especially as a system).
Windows for the most part is a poor development environment. It can work fine, but the more nice to haves can be a pain to set up. Composer is one of them.
Many issues you describe are to do with composer. Composer is a dependency tool, it installs dependencies for you at (hopefully) the correct versions. That's the entire point of it. Composer itself is not maintained by Silverstripe (so complaints about the tool and it's usability are misdirected), nor are many of the packages people create for it (module and/or theme authors should be consulted). Any dependencies missed by composer mean they're either not listed as dependencies, or the thing you're trying to install is outdated for the version you're attempting to install it to. And the fact that you're copying composer commands indicates that you're simply not familiar with the tool. This is also not the only way to install things with Silverstripe - just the suggested method as most PHP development is done this way these days. It is 2015, not 1985.
Silverstripe does not show pictures of themes anywhere, these are not installed through the CMS. This is by design.
If you're talking about images loading when selecting a theme via a gallery of some sort, then the issue is more than likely with your internet connection (which seems unlikely), or by theme authors not uploading preview images when registering their theme. If you're talking about http://addons.silverstripe.org/add-ons?type=theme - then this is because you misunderstand. This search tool simply lists composer packages listed on packagist.org with a silverstripe tag. Again, it is up to the authors to supply previews, etc. usually via their github repository's readme. There used to be a 'theme gallery' on silverstripe.org, but it was so out of date that it wasn't doing anyone any good.
So that brings us to the point that many of the things you've mentioned are quite outdated. You are trying to install an eight year old theme (the default for 2.x) on a brand new 3.1 installation. It is of course up to the developer to check the dependencies listed and make an informed decision on what they're doing. There is only so much automated tools can do.
You seem to have managed just fine in the past http://www.silverstripe.org/ForumMemberProfile/show/4786 so I'm wondering what this post is really about since most things are not to do with SilverStripe, but more with learning curves. While none of the points you've raised are particularly invalid from a new user help perspective, they're more to do with the usability of either this site or some other unspecified one, and the wide spread 'misinformation' around other old sites/blogs.
The most relevant point is about windows development with WAMP, and is of particular interest to me. I have experienced extreme slowness in the past too, but after the first load it is usually not too bad. I wonder if it's purely to do with my under-powered machine, the windows environment (and WAMPserver.com in particular) or a combination of them both. I suspect more of the former. Would you mind sharing specifications of your development machine?
Silverstripe is known to be reasonably memory hungry, but once it has formed a manifest, built a database, and resized asset images, it isn't so slow. One must of course understand the limitations of the system they're attempting to develop on. That said the performance of silverstripe is an ever evolving battle that the core developers attempt to improve.
