For computer based flac -> wav decompression, click on the server settings tab, then file types. Be sure the only box checked regarding flac is the one that says file format flac and stream format wav and click change. You'll need to stop and restart or change songs for this to take effect.
To use a remote computer to access your slimserver, go to <your server's ip address>:9000 For instance, mine is 192.168.0.100:9000
Something no one mentions is that your server is also accessable from remote computers unless you disable it (ie, if i know your ip address, i can control your slimserver. This also depends on router settings). To disable this, go to server settings, then security. Go to the Allowed IP Addresses box and put in 127.0.0.1,<your range of ip addresses> and click change. For instance, mine is 127.0.0.1,192.168.0.100-105