It’s not open source, but Tumblr is a decent option if you want something fairly easy to setup. Additionally, it can look very professional with a good theme..
As others have already mentioned, Pixelfed is probably your best option for a FOSS solution to your problem.
In my experience larger packages (in terms of file space requirements) install slower, but download speed is a factor there too.
Cancelling compilation is safe to my knowledge. No changes were made as you stated. Just remember that the downloaded files will probably still be in your cache afterwards, so you may want to remove that with paccache.
You mention “partial installs,” but the actual issue is partial upgrades. A partial upgrade is when you don’t upgrade the entire system, but only one or more packages. A partial install isn’t really a term people use, but could probably refer to installing a package without its dependencies being installed.